I've seen serious traffic on my church's website this month from Googlebots. Last year I added a Calendar to the site using the ical standard, and now the Googlebots are pinging the heck out of the php pages rendering the calendar. We're talking 90% of the site's accesses have been from Google this month.
My prediction is: Google Labs will be releasing a Google Calendar tool soon. You heard it here first.
The fact they are attracted to the ical standard is cool...maybe it can take off with their support.
UPDATE (2/24): Since there seems to be so many folks linking and reading this post, let me add a couple bits:
1. My guess is that Google Calendar would be a search tool, not a calendar application.
2. If you are interested in a cool calendar tool, check out Mozilla's Sunbird which can be rendered on the web using SourceForge's PHP based Calendar.
3. This is just a guess based on traffic on one site. Even if they are working on it, it may never get out of the lab.
4. Here's the stats I based my prediction on: