The original source of this report, MacInTouch, isn't a rumor site. I'd classify them as one of the best and most reliable Mac news and commentary sites on the internet. IMO, if they report something you can be almost certain that it is true. And if they are wrong I'd bet that they would be the first to correct themselves.
With the possibility of no live keynote broadcast, I think everyone should reset their expectations on what will actually be introduced next week. It could be a lot less than the rumors have suggested.
Of course, nothing would prevent Apple from changing their mind on Monday and actually doing a live video broadcast of the Tuesday keynote. Thus, maybe Apple is trying to artificially lower expectations in an attempt to control the run up prior to the keynote -- that is, attempt to cool things down and then hit us with everything they've got -- $500 xMac, flash iPod, iWork, etc. I hope the latter is true.