I recently discovered "Google Apps for Your Domain" and it is really great (thinking about moving the entire company to it). I was experimenting with GoogleCal and it is rather well done. I still had a problem with it because I could not sync it with Ical but I discovered this great utility, Spanning Sync. No matter what Tech Crunch says, I am still uncomfortable moving 100% to web app only ;-)
Now I can sync both ways Google Cal and Ical and can give read/write access to my cal to my assistant (she could only read it before with .mac). AND I can sync Google Cal with my Blackberry !
BTW, I have just replaced the default Sync tool for blackberries for Mac (Pocket Mac), it was terrible. I found The Missing Sync for Blackberries and it is so much better, well worth the extra cost.