I agree. I think this is just one step towards a full virtualization system in Leopard. I think this is really all a part of Apple really dedicating itself to getting users to switch and to increasing it's market share.
However, there are always going to be applications that won't like a Virtual Machine (at least for a long while). Intel will need to hardware accelerate virtualization a lot more than has currently been implemented before I'd want to run Call of Duty 2, Oblivion, or Unreal Tournament 2007 (you know... when it's done) from inside a Virtual Machine! There are other important non-game applications where raw performance still matters too much (AudoCAD, Maya, 3DS, and AVID/Final Cut Pro come to mind among others).
Is it a gamble for Apple? Absolutely. It could be that this drives developers who may have considered switching from Windows-only to OSX to hold off. But that logic only holds assuming that Apple's gambit doesn't pay off. Even if they only get 5-10% of Windows users to buy a Mac as their next machine (now that they have a safe out and can switch back to Windows if they want to), that's a huge increase in market share for Apple. And Apple is cool right now with iTunes and the iPod and all, so I think at least that many people will be intrigued.
I bet at least 1/2 of those people will like OSX (probably a lot more). It is pretty slick to use (I was a die-hard Windows guy before I started my job that required me to use a Mac) after all, and it's very geek-friendly (UNIX shell and all that). If that happens, and their market share continues up not down, it will drive development, not discourage it.
I'm just frankly stunned with all the changes Apple has been making (this, the Intel switch, the two-button mouse). They certainly aren't being complacent with their recent successes. It will be interesting to see where they go.