With the new regime at MS this last year or so came new advertising/marketing & PR partnerships. Aside from the occasional WTF (Seinfeld?), they've been doing a pretty good job as a whole.
As someone who was in the ad/pr industry for quite a long time I can tell you that:
1. The date has "leaked" reliably pretty much once a week on all the betas to date. Nothing's "leaking". They're disseminating the info virally to build buzz. It works, and that's ok.
2. Win 7 needs as much positive spin as it can get to offset the Vista catastrophe. The february beta was more stable and bug-free than Vista SP1... and to coin a phrase "it's Vista without the suck." They need to get the word out there, to as many folks as possible. For Windows, it's not bad at all, and it's a massive improvement over Vista even if they share 80% of their DNA. Well, aside from the start menu still requiring Vista's 50 clicks to get to the app you want due to the teeny-tiny scrolling programs folder list. I don't like some of the interface Nazi choices that they're making with no user overrides available (start menu, ribbon).
Look, I've tried the public beta back in Feb, and I'm looking forward to putting RC1 on a couple light use 3D workstations. There's nothing inherently wrong with the XP64 that's on 'em, excepting that fewer and fewer 64-bit apps... like say MacDrive... run against XP64 (just Vista.. which is a naggy, broken clusterfuck).
I'm happiest on my primary workstation (which is a Mac) and my laptop (also a Mac), but I've got memory & processor intensive CG apps I run that require Windows 64. Some require Linux 64. Diversity is good. Rendering throughput with Win7 beta (Maya/mental ray) was nearly 10% higher than XP64 and on par with Linux 64's render times... just easier to roll out and configure on a bunch of render slaves with random hardware profiles (ie whatever I've got on hand when I need the horsepower).
Anything that makes Windows suck less is fine by me, and getting a viable 64-bit Win OS in my hands before I'm unable to buy OEM XP64 copies anymore is a priority. Having RC1 not expire until mid 2010 is a bonus. That means I can use it in light production as a render box or secondary workstation now instead of a nuke-every-few-weeks sandbox.