Some of these announcements include:
- Using the iTunes store as the distributions channel (expected)
- Apple will be the approving authority and gatekeeper for all applications
- There will be no connectivity allowed to third-party add ons
One final note: iLounge's source says that the March event will be used to announce a beta version of the SDK and that Apple's June World Wide Developer's conference will be the actual ship date of the final SDK build.

This is why Ziphone and the like will never go away.
Love my iPhone.. but Apple is a bunch of idiots.