Google announced multiple calendar sync support for iCal.
We have tested this in-house and it seems to work well on our systems. Full two way sync for multiple calendars, which is very nice (and the changes are immediate).
Using OggSync Windows Mobile and PC Outlook sync with this version, plus adding Google’s Blackberry multiple calendar sync gives an enterprise pretty good coverage for syncing syncing multiple Google calendars to most of the desktops and pda devices people use. If you are interested in a domain or an enterprise license for OggSync (Pro version for everyone in your domain or enterprise), please contact us at firstname.lastname@example.org.