Another theme at the PDC is that Microsoft is trying to be more "open" and draw developers that use other technologies such as PHP or Java. Certainly Microsoft would love to have these users in their corner, but what in Azure will appeal to them? At the moment it seems just the opposite; after seeing the demos I cannot imagine trying to use Azure without the help of Visual Studio's IntelliSense, for example.
Microsoft certainly admits that Azure is a "nascient technology", as Ray Ozzie put it in his keynote. That's wonderful Microsoft-speak for an unfinished product. Yet even when it's finished it seems like it would be difficult, perhaps impossible, for anyone to use Azure effectively without buying completely into the complete Microsoft environment. Microsoft is playing to its developer base rather than reaching out to independent developers. That would seem to make Azure a pure defensive play, so current customers have a place to go in the cloud.