Don't forget you will need the corresponding MT flywheel, and you will need to add wiring/provisions for the trans fluid quality/temp sensors, and clutch switch which the DME will be looking for with the 6MT DME flash. I'd upgrade to the 2009/10 diff as well while you're at it. It's a good security at ~300$ or so.
Some other obvious, already mentioned items:
Associated tubing for hydraulics
master reservior cut for fluid drop down to slave
instrument cluster software/coding
driveshaft (Length difference)
necessary console trim/boots
Shift linkage (Might as well weight the rod while youre in there.)
7842647: Non US cars with bad fuel quality and a lower service interval on oil changes.
7842502: US SMG and Korean Cars. *
7842641: Non US cars with bad fuel quality.
7842645: Non US cars with some kind of CEL parameter change**
7842795: Japan's version.
7842643: Non US cars with bad fuel quality and a CEL Parameter change(see 7842645 but with bad fuel).
7842649: Non US cars with bad fuel quality and a CEL Parameter change(see 7842645 but with bad fuel) and the lower service interval.
7842639: Non US cars standard tune CO2***
7842504: US Non SMG cars
7842799: Targets The New Euro CO2 standards. This requires a new code file flash as well.
Thanks to M5B user "Ferris" who seems to have access to BMW's SWL system, or did at one time.