That's right, Visual Studio 2008 includes "multi-targeting", which allows you to build solutions targeting the framework 2.0, 3.0, or 3.5, all from the same IDE. So the natural next question is, can I use Visual Studio 2008 to continue building and maintaining my .net 2.0/VS2005 based solutions?
The answer is yes--- with a caveat.
The solution file format has changed between versions of Visual Studio, so you're going to be prompted to upgrade your solution when you open your original solution. A nice wizard (hey, we're Microsoft, after all) will step you through the process, and back up your original solution files for you. Once you've done that, you should be good to go. However, the original solution location will now contain the updated file format, which you can't open in VS2005.
Hey, nothing's every perfect... 🙂
However, as many people have commented, you can indeed open project files between versions, which is nice.
So go nuts! Give VS2008 a try! It's available for current MSDN subscribers via subscriber downloads right now! If you are planning to purchase VS 2008, download and install the 90-day trial editions to get started, before you can make that official purchase in January!