Microsoft's current public statement says that, apart from Windows Phone 7 development, there will not be Smart Device Application Development added to Visual Studio 2010.
This obviously raises concerns and has implications for a lot of people, and there are more than a few of us lobbying Microsoft very hard to change that plan and to get them to include some sort of support for Smart Device programming outside of Windows Phone.
I'm hopeful, maybe even optimistic, that their stance will change and that we will get something - even if it's only CF 3.5 targeting actual hardware (i.e. no emulator support) - at some point down the road. Right now they've got all hands on deck trying to get Windows Phone out the door, and until that happens, I wouldn't expect much for resource allocation toward other device features.
So what does that actually mean? In my mind I wouldn't postpone installing VS2010 until they have device support. My guess is it won't happen until early next year at the absolute earliest and realistically I would say mid to late next year if it happens at all. Again, I'm optimistic that it will, but I'm also a realist, so I'm not going to base my business decisions and future on it happening.