No, support for native DOS has been completely phased out. As you are probably already aware, the command prompt in Windows is NOT DOS, though it does function in a similar manner. To the best of my knowledge, though, there will never again be native support for DOS or DOS-based applications.
As the previous poster noted, you can use the emulator DOSbox, which I used myself and have found to be a very competent emulator, though certain more advanced games may not run as well. Be aware also that when you configure the emulator, you're actually telling it how many processor cycles and how much RAM you want it to suck away from Windows processes. If you run DOSbox by itself, it's not really an issue, but if you want to run it in conjunction with your normal Windows programs, it can be a performance issue depending on what you're doing at the time.
I am probably going to be installing the Windows 7 beta sometime this week. If I discover anything different, I'll try to update this answer.
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