Recently, I’ve stopped using OsaSync to keep my email synchronized, and moved over to gmail’s IMAP support with Outlook 2010. This made it much easier to synchronize my email, however, there was no way to sync my contacts or calendar items. I did some searches, and turned up gSyncit.
It handles syncing all your calendars and contacts to Google’s Calendar and Contact services, and from there to however many computers you’d like to connect.
It supports multiple calendar support, along with one way or two way syncing,with a whole host of other options. It even supports filters/categories, so you can sync only certain appointments. The same options apply to the contacts as well.
About the only thing that this can’t sync is your Outlook tasks, but that’s cause Google hasn’t opened the API for tasks yet.
It’s only $15 a license, and if you use outlook and gmail, it’s highly recommended. You can get it here.