Payment methods include single use, unlimited use, and time-expiration based. Subscriptions can be implemented "by writing some minor ASP code".
News.com quotes Dave Fester, Microsoft's director of marketing for the digital media division, in an article as saying "the delivery of the Digital Broadcast Manager is a huge step in enabling service providers and partners to create profitable business ventures with digital media." This article can be found here.
It sounds like a great idea, but actual demonstrations of their method of implementing these secure downloads and payment remains to be seen. Please add a comment to this article if you get the opportunity to try out this software or hear any more information about it. Release of the product is said to be Summer 2000 (hey, it's summer here in Australia right now :p), and pricing will be announced later.
Do Real or Apple have anything like this happening yet?
Some more information from Microsoft is available here and developers who are interested in signing up in the DBM Developer Preview Program should visit this page.
Unsurprisingly, according to the FAQ on the Microsoft site, DBM will only deliver in the Windows Media Player format...