According to a post on the DEV-TEAM Blog and the subsequent comments, it looks like there bunch of activities aroung the iPhone 3.0 Beta is going on.
But first and foremost they were asking not to upgrade to the new IPSW if you are running YellowSnow because you cannot go back to IPSW 2.2.1 and restore Yellowsn0w.
"And for those wondering, yes the 3.0 OS is jailbreakable on all devices. It’s just those using 3G yellowsn0w that have to show some restraint and wait for PwnageTool to create a custom IPSW that avoids the baseband update."
The discussion is going on and most that I gathered is from it that without a DEV IP from Apple people are going to have trouble if they upgrade to IPSW 3.0 Beta.
You can follow the post and the discussion at Itchy update fingers on DEV-TEAM Blog