If any of the Googlers-in-charge are listening, here’s my pure-gold tip of the day:
Buy a license of Microsoft Exchange ActiveSync Protocol.
With the rapid adoption of this protocol as de-facto standard for mobile email client synchronization and proliferation of Windows Mobile devices, it’s a no-brainer.
I bet it will take a couple of nights for 2 of your over-caffeinated server gurus to hack together GMail and Google Calendar support for this, making it possible to sync any ActiveSync-enabled client with your server data.
And then you will offer an ever-too-tempting alternative to the business users who have to stick with the Microsoft Exchange at this time, giving sad, longing looks to your cool email and calendaring suite.