Microsoft will offer an application marketplace within Sharepoint 2010 that shall integrate with third-party applications from its partner network. No date has been set for the marketplace lauch but it will evolve from "The Gallery" a feature that provides Sharepoint 2010 users access to templates.
Via twitter link leahsoleil
IMHO this is big. Again nothing new, even Apple could figure this one out with the iPhone allowing other people to build the killer apps for their platform, but given that SharePoint is so much more than just a Mac toy it could have a very large impact on the workplace.
And potentially very disruptive. But for us SharePoint consultant and developers this will open a great number of opportunities.