It has been observed that there were some bugs in the new JailbreakMe.com jailbreak,which affected iPhone 4  users. These bugs generally got rid of FaceTime and MMS Icons, so users lost functionality with both those apps.Comex tweeted today that the bugs have been fixed, and  for users who are still faced with these bugs there is a quick fix available right here. All you will  require is some knowledge of WinSCP. If you have that then you can proceed with  this tutorial,if not then you can simply restore from back up and re-jailbreak your iDevice.If you know how to use an SSH program or iPhone file-viewer you can easily fix Facetime or MMS bugs caused by the new jailbreak.



Note: Comex has fixed this error as of this morning, so new jailbreakers do not need to worry about this. 

How-To:

chmod 755 /private/var/mobile/Library;
chmod 755 /private/var/mobile/Library/Preference
reset Network Settings

Once you have completed the tasks listed above you will now have FaceTime and MMS working on your iPhone 4.