On Jesse's Digital Playground webcam show last week someone asked if Jesse was going to work with BiBi again soon; Jesse then just went off on BiBi, saying how much she hated her, how BiBi couldn't handle either Jesse or the industry, how BiBi cried after every scene, how much she hated her (again), how BiBi's gross, etc.
If you're a twitter stalker, Jesse tweeted back in March (26 or 27) that some girls weren't cut out for the industry and that she made a bitch cry - something like that, if you're interested the tweets are probably still up; a few hours later BiBi was tweeting about a massive headache and how someone bounced her head against a concrete wall - one of the filmmakers commented that it was painful to watch. Since then, their tweets make it look like Digital Playground hasn't had them both on the same set since. The way I'm putting 2+2 together is that Jesse might be violent and really, really, really doesn't like BiBi.
I don't know what the basis is - they seemed pretty close at the beginning of the year - but there probably is some jealousy: the webchat took place right after BiBi killed in a solo interview on Howard Stern to promote a movie that they're both in. And in pure conjecture? Jesse probably sees BiBi as the (or a) long-term replacement for herself at Digital, so there's probably some bad blood just because of that. Someone was writing that Jesse going off like that might have been a reason why Digital Playground keeps losing so many starlets after only a few months.
And then there was the twitter war Jesse unloaded this morning at 7am. I have no idea what brought that about, but Jesse deleted everything she wrote within the hour; she was typing like she'd gone crazy. It's a hell of a lot more engrossing that 'The Kardashians'.
So from what I've read, I doubt it's for publicity. I'm not really a
Jesse Jane fan so I don't know what she's about, but I haven't seen/heard anything that BiBi/Britney has done to her, so I'm guessing jealousy.