Cpich (iPhone dev-team member) just sent a tweet mentioning that he know from trusted source that Apple will release the new version of iOS 4.0.2 that will close the security hole to make the JailbreakMe 2.0 star not work.
A little birdie told me ios update due in a few hours (better to believe than ignore) so go ahead and save your SHSH before it’s too late!
So, I highly recommend that you should save your SHSH blobs to let you restore to a firmware version that can be jailbroken and unlocked. see guide posted here.
Update:Apple already released iOS 4.0.2 for iPhone, iOS 3.2.2 for iPad to Patch JailbreakMe PDF Exploit here.