I believe there is. There's a couple of apps that will convert from iCal to Google for the Mac, and from Outlook to Google on the PC.
However, it would be much easier (presuming you have a MobileMe account and Outlook on your PC) to go:
iCal <--> MobileMe <--> Outlook
No Google calendar required. And with MobileMe, you can still edit your calendar online, and iCal can publish a read-only version for anyone to access. May not be the best for people who need heavy business calendaring, but for many users, it works very well.