Microsoft's existing nearly-free-licenses-to-help-developers-get-going-on-the-platform program has been around for a while and has always required that a company plan to distribute a "packaged and resalable" application targeting a Microsoft platform.
It could be an app on Vista or Server, an Office add-in, a Windows Mobile app, or one of a few other options. But it had to be packaged, at least in the sense that it was digitally bundled into an installable set of files even if it never got put in a physical cardboard box.
This requirement made some sense as far as promoting the client OS ecosystem but it disqualified any online offering. An online service had to work around the restriction: for example, by offering a small Windows Mobile app that has some interaction with the service.
But the language makes a statement -- Empower was largely about helping ISVs new or old develop apps on the platform, thus making the client platform stronger. Nevermind that an online service that targets browsers and the iPhone might lead to Server license sales later.
BizSpark, on the other hand, takes another approach. There is much talk of online solutions -- the program is meant to dovetail with hosting providers (or Microsoft's Azure platform) to offer the server-side muscle a solution will need after its incubation period. The program is aimed exclusively at new companies -- if a firm has been in business 3 years or more, it does not qualify.
Both programs exist today and will presumably continue. So I'm not suggesting there is a big move from one view of the world to another. But there does seem to be a conscious broadening of horizons in terms of seeing where innovation is taking place and how Microsoft can be part of it.