We have no idea. There was a thread where a developer named bdroad was posting about email and calendar updates, but like so much other material on this forum it was deleted.
Keep guessing with the rest of us.
If one is developed it will "probably" (my opinion) come from a third party develper. A user named bdroad announce that his company was working on a synched calendar for the Instinct with estimated dates. However, his company/bdroad requested the forum administrators to remove the post. My "guess" is they were not ready to announce anything official yet or commit to dates.
calendar, pda like features - are you kidding??? this is a MEDIA phone. Sorry, that is what I was told AFTER I bought it. Ooops, I thought it was the iPhone KILLER so I bought it the first day. Still no worth-while calendar. Still I swim in pain.