Not according to Jesse Liberty.
You will want Blend 3 for its terrific designer and animation capabilities and VS for its development capabilities. Microsoft is trying to make these tools the best for their target audience, rather than one tool that does everything merely adequately.
The other point Jesse makes: Because it is a few months old at this point, the Blend 3 beta won't work with .NET 4 projects yet. If you want to work on projects in VS 2010 and Blend 3, create them as .NET 3.5 projects.