Store nearly always goes down between 5-6am Cupertino time if there is an update for that day. So, if the store goes down in the next hour then there's a chance of an update today. Otherwise, there's next to no chance.
BUT If its a major redesign why would they lauch them with no event. when has Apple ever annonced a redesigned product withinout an event apart from the Macbooks but they wernt really that different. Imac G5=Event= Imac G4=Event and the original imac had a massive=Event. Sadly i dont know how long were going to have to wait. IM SO DESPEARTE FOR A NEW IMAC though. I might buy a mbp but i hate laptops and think that the MBP is bit old eg. Powerbook G4, it still has a mechanical latch for goodness sake.