No, it's not happening today.
The 17" MBP was widely expected and there was good justification for believing it was going to be launched. If you'd asked me, I'd have said the bets were on for that. It's a relatively minor update (it's the PowerBook 17" replacement, using the MBP design), and most importantly, it occured at an event consistant with the type of product being announced.
There is no reason on Earth to believe the MacBook will be released today, or any time in the next week (and probably two weeks.) The MacBook WILL, for the reasons I gave, be released at an actual event, almost certainly a press conference organized specifically for the product, or for it and some other new product announcements.
No such event has been scheduled, for today, or any day next week. Ergo: no MacBook announcement today or next week (the probability they'd announce such an event to take place in less than 7 days is minimal)
If Apple just released the thing by announcing its availability on the front page of Apple.com, it would be the most stupid marketing decision in recent Apple history. This isn't some minor update, it's an entirely new series of computers, a fresh set of machines that cannot be seen as merely an upgrade or Intelization of an existing model. To date, every single Intel-based Mac has been announced at an "event", not just on a website. The MBP 17" had the lowest key presentation, and it still meritted a launch event, albeit a minor one. Why on Earth are MacRumors readers convinced such a thing will happen with the MacBook?
No MacBook until the week commencing 8th of May at the earliest. I guarantee it. And if you haven't heard of an "event" by Wednesday, you can probably bet it'll not be until the 15th at the earliest (keep adding 7 for each Wednesday that goes without an announcement.)