YES! Official support statement:
The core Visual Basic 6.0 runtime will be supported for the full lifetime of Windows Vista, Windows Server 2008 and Windows 7,which is five years of mainstream support followed by five years of extended support
I don't know when it was changed, because it didn't say that a couple of weeks ago, but it does now. Hoorah!
As VonC pointed out in his answer, the IDE is not supported any more, which is a worry if you want to maintain and update your VB6 code.
The Visual Basic 6.0 IDE will be supported on Windows Vista and Windows Server 2008 as part of the Visual Basic 6.0 Extended Support policy until April 8, 2008
People have been using the IDE on Vista with a few tweaks. And if necessary it will always be possible to run it in a virtual machine.