On the last episode of the CheapAssGamer podcast, CheapyD stated that he knows "for a fact" that Sony will show a PS3 XMB redesign at E3. He doesn't delve into what changes will be implemented or if it'll have new features like cross-game chat, but it's certainly something forward to. If true, they'll likely release the firmware the same night of the announcement.
Since Sony hasn't officially stated any such plans, this is considered a rumor for now. We'll know for certain in a month.