I am trying to consolidate information as i have been messing around with my phone for 15 hours in the past 3 days.

MMS:
It appears that all the mms fix packs edit the com.apple.mms_override.plist file

Something changed in 4.1, and that is why none of them work.

you can use the default settings of

epc.t-mobile.com OR wap.voicestream.com OR internet2.voicestream.com
http://mms.msg.eng.t-mobile.com/msg/wapenc
216.155.165.50:8080
1048576
http://www.apple.com/mms/uaprof.rdf

you can send with epc.t-mobile.com, but you will get the size restriction error message when receiving.

wap.voicestream.com and internet2.voicestream.com, sending is VERY intermittent, but receiving is 20 minutes delayed

I have tried editing the .plist file, ipcc carrier packs, patching the commcenter, everything.

Solution: wait for a 4.1 specific MMS patch to be released.

Facetime:

follow @pushfix on twitter and wait until MiTime is ready for 4.1

For all asking about the Cellular data network tab:
after jailbreaking, pop your remove and reinsert your sim card, wait until you get reception, you should see Carrier 8.0 under settings>general>about>carrier. NOT AT&T 8.0