Announced this morning by the official DDR Twitter account, Dance Dance Revolution V is coming to PC, based off of the latest iteration of the arcade machine. Currently it's in open alpha form and contains 15 songs, there's just one catch: you need to go through Konami's Japanese site and register a Konami ID, if you don't have one already.
"Alpha" is the best way to describe this project at the moment, as timing is a bit off and the online app is very barebones. At the very least, keyboard controls and dance mats are supported, and you can go fullscreen.