I use Skype a lot, so I'm right now restoring to 4.1 using Tiny Umbrella, and then I'll update to 4.2.1, install Skype first, and then jailbreak again.
Will report back soon...
How do you keep your baseband at 1.59.00 after all the restoring back to 4.1 and 4.0.1 and stuff like that?