Having just watched GTTV with Don Mattrick, he says "I know the price. I think you're really going to like the price. We sat through the other competitive press briefings and we were very pleased with our position. I like being at Microsoft this holiday. I can't imagine he'd be that optimistic with a $150 price tag. He must know that nobody is going to "really like" that price.
He also said that they didn't give the price at E3 because they wanted to "get more coverage". "We can have another press release, and I can come and talk to you again". I think they're planning an announcement at Gamescom (Microsoft - "We will have a much bigger and more spectacular appearance at gamescom this year than we did last year"), and it's going to be cheaper than people are expecting. $99, I think.