Note the wording of the invitation. It does not say that the SDK will be released on March 6.
The “exciting new enterprise features” could be interesting. Some guesses:
- Exchange push support: Huge, but unlikely.
- Over-the-air calendar sync: Huge. Possible.
- Security crap: Various enterprise-desired security features like memory encryption, over-the-air deactivation upon theft, etc. Boring. Possible, but unlikely.