Perhaps it's an oversight--but with all the high profile exposure microformats have been getting lately it's kind of hard to imagine. But people have deadlines and some things just can't make it into the first release--even at Google. The main thing, as Mark Pilgrim says is:
Sniping from the sidelines makes us look petty and insular. Instead
of making assumptions about big bad evil Google ignoring open
standards and locking users in, have we tried opening a dialogue?
I don't know anyone at google so I feel like I'm doing my part by just blogging about how awesome it would be if they marked up their calendar data using hCalendar. As a full featured calendaring application on the web, Google Calendar could really enable downstream applications like the LiveClipboard if they simply added some class attributes and spans to the data they are already displaying.
In the long run I imagine it's in Google's best interests to promote microformats since their infrastructure would allow them to take best advantage of a system of distributed metadata. Here's to hoping that it'll be layered in sometime soon. In the meantime Scott and Mark have the right idea!
By the way, being able to enter a quick event in free text and have the time/location/description parsed as opposed to tabbing around in a complicated form is very nice.