Considering their recent press coverage, I don't see why that would stop them. They probably wouldn't want it to interfere with the press coverage of the new phone launch, but after that is over I think they would be willing to take some bad press in order to make sure that there are repercussions to doing something like this.
The other possibility is that Gizmodo & Gawker would never receive invitations to future Apple product unveilings/announcements. I'm sure they got a decent bit of traffic during the iPhone OS 4.0 live blogging feed. Jobs likes to hold grudges and if you get on his bad side, you'll probably be blacklisted for a few years at least.
I don't think it's going to happen, but if they wanted to hurt Gizmodo without going to court they could add Engadget to the short list of media outlets that get early review units.
I bet this will happen. Apple are known for alienating companies that go against the wall of silence. There are more than enough people who 'live blog' every Apple announcement. Cutting them out will make a point and not harm Apple.
