In case this is helpfull to anyone else out there at somepoint (All for '07 Z4MC):

#1: Diff Chattering.
Apparantly got the OK from BMWUSA that my model car is approved for the new type of diff fluid. Scheduled in on Friday for the change. See if it helps.

#2: Clutch pedal 'catching' or 'grabbing' on release.
Unfortunately, this only happens when the car is cold, so everytime I get it to the dealership the car is warmed up and the clutch pedal feels perfect. As an attempt to remedy, the dealership is ordering me new bushings for the pedal. May or may not install on Friday depending on time.

#3: Stereo goes to sleep for a couple of minutes upon car-start after synching my Blackjack cell phone.
Was told by my the dealership the phone isn't supported. Un-synched the phone and the stereo worked perfectly. Re-synched the phone, and the problem returned. Issue is minor enough I really don't care. Hands-free safer than hold-cell-phone/steer/shift.

BTW....I love this car. It's just magic. These issues are very minor to me and don't effect what a stunning machine the Z4MC is. Luuuv it.

Which local dealer is performing your work? Who is your Service Consultant?
What "new" differential fluid is being installed. The current specified fluid is Castrol SAF-XJ, P/N 83 22 1 467 993 for one liter.
Have you done the clutch delay valve modification? That mod may address your clutch release issue. I can't imagine how new clutch pedal bushings are going to do anything for the release.

BMW NW in Fife. Working with Dave and Jon.

There is apparantly a known issue with the diff's in the e36 M3's....which my '07Z4MC shares the same diff. I have no idea of the detail of the new fluid. I just went through my 1200 mile service a few weeks ago. This is an entirely different type of fluid than used in the 'standard' changes I'm told.

I really don't think the CDV is the issue. I am not good at describing the problem. When the car is cold, the pedal with 'catch' when you SLOWLY release it. Car doesn't have to be running. Once warm, the clutch pedal action is as smooth as silk.

BMW NW in Fife. Working with Dave and Jon.
There is apparantly a known issue with the diff's in the e36 M3's....which my '07Z4MC shares the same diff. I have no idea of the detail of the new fluid. I just went through my 1200 mile service a few weeks ago. This is an entirely different type of fluid than used in the 'standard' changes I'm told.
SNIP

I think you mean that the E46 M3 and the E86 Z4M share the same type multi-plate limited-slip differential that calls for SAF-XJ fluid.
This is the problem you are experiencing:
http://www.m3forum.net/m3forum/showthread.php?t=86605&highlight=Differential+fluid&page=13
What BMW NW will probably do is install the SAF-XJ with FM Booster fluid P/N 83 22 2 282 583 per this SIB:

SI B33 01 02
Rear Axle December 2003
Service Engineering
This Service Information bulletins supersedes S.I. B33 01 02 dated June 2002.
SUBJECT
Grinding Noise from Differential During Slow Cornering
MODEL
E46 M3 from start of production through December 2003
SITUATION
A grinding noise may be heard coming from the differential during slow cornering.
This noise is best heard during tight cornering situations for example parallel parking, driving in a tight circle, etc.
CAUSE
When the rear wheel speed differential varies during tight cornering, a slip stick effect is created on the lining and steel discs incorporated in the differential locking clutch causing a grinding noise.
This noise typically goes away as the locking clutch discs in the differential break in.
Break in time varies depending on driving habits, for example more tight cornering (working the locking clutch) = less time for breaking in the locking clutch discs.
CORRECTION
If a customer complaint is verified as described above on E46 M3 vehicles, the differential oil should be replaced with specially formulated differential oil, BMW part number 83 22 2 282 583.
PROCEDURE
1. Drain differential oil. See E46 M3 repair manual, group 33, section 00 11 259.
2. Refill differential with special differential oil as shown in the illustration below.
Differential fill capacity = 1.2 liters (1.3 quarts).
3. Road test the vehicle.
With the vehicle at operating temperature, drive in tight circles (20 circles in each direction) allowing the special oil to coat the locking clutch discs.
The grinding noise will be eliminated when the locking clutch discs are sufficiently coated.
Note: Vehicles that have had the differential oil converted to this special oil should continue to have this oil utilized whenever a service requiring differential oil replacement is indicated.
PARTS INFORMATION
Part Number: 83 22 2 282 583
Description: Special differential oil kit
Contains 3 bottles - .5 liters (.53 quarts) each
bottle (order quantity 1 rounds to 3 bottles)
WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty.
Defect Code
33 10 92 39 00
Replace differential oil with special oil

I installed that fluid when I did the 1200 mile fluid changes.

#2: Clutch pedal 'catching' or 'grabbing' on release.
Unfortunately, this only happens when the car is cold, so everytime I get it to the dealership the car is warmed up and the clutch pedal feels perfect. As an attempt to remedy, the dealership is ordering me new bushings for the pedal. May or may not install on Friday depending on time.

I have this issue or one that is very much like it.. also only when cold. Just started in the last week or so. But - my problem feels like a clutch engagement anomoly, not the pedal catching or grabbing, though at first, I thought that was what it was. Once the car is warm, it no longer happens. Next time you drive your car, conciously monitor how the pedal feels as you're feeling the weirdness.. make sure it is indeed the pedal and not how the clutch is engaging/grabbing/slipping/whatever. If we both have the same problem, we can share the fix once discovered.. thanks!

Talked to Jon at BMW Northwest and he indicated they had to get Zone Rep approval to apply SIB 33 01 02 to your E86 Z4 MC. They did in fact install SAF-XJ plus Friction Modifier, P/N 83 22 2 282 583, in an effort to eliminate the differential grinding sound. Fortunately you got it covered under warranty.
Currently there are no SIBs addressing Group 33 (Differential) on the E85 or E86.

Well....color me feeling special....
Took the long way home and in the wet weather and definitely got the diff working a couple of times....once big time. Haven't experienced the 'issue' yet. Interesting on the break-in comments. Wonder if it just would have gone away on it's own.

KevinC: I have the new bushings now, so will wait for next cold-start. (Tomorrow). See how things are. That said...my actual clutch engagement has been very consistant. Has been really specific to the clutch pedal feel. Nothing more.

Follow-up.....two cold-start mornings and smooth as silk clutch....so the replacement bushings appear to have done the trick. Cheers all.