I think I'll be staying on 4.0.1
Re. the "old method" of Jailbreaking:
Doesn't (currently) work on the iPhone 4, or the 3GS on iOS4.
The iPhone 4 can't (currently) be Jailbroken any way other than using Jailbreakme.com on a device running iOS4.0/4.0.1.
The only (current) non-Jailbreakme.com method for a 3GS on iOS4.0/4.0.1 is to use PwnageTool (Mac only)... and it'll only work if the 3GS has the old bootrom & has previously been Jailbroken. PwnageTool also works for the 3G, whether it's previously been Jailbroken or not.
Hopefully the DevTeam has some holes hidden away, ready to update Redsn0w once Apple releases iOS4.1...
For Jailbreakers on iOS4.0.1 (and for owners of the original iPhone, or the 1st. generation iPod Touch, both apparently ignored by Apple regarding the PDF exploit fix, even though they are just as vulnerable):
"saurik" (of "Cydia" and other things) has released a fix to patch the PDF exploit:
http://blog.iphone-dev.org/post/9414...hat-apple-wont