Sony's event is HEAVILY rumored for June 3rd. Both Jason Schreier, ZhugeEX, and Jeff Grubb have corroborated on it. I think this would be a fun poll to see when Sony will actually announce it!
All the days that make sense come to pass so umm... Friday. If not Friday then Monday makes sense. If not Monday then Tuesday makes a lot of sense. If Tuesday doesn't cut it either I can a see a surprise announcement on Wednesday before the reveal itself; it makes sense.