If you add a contact via Gmail you can add the persons birthday which in turn you can sync with your Google calendar. But if you add a contact via your phone book or what ever you want to call it there is not a option to add a birthday. I could be wrong but poked around for quite some time and didn't see it. If it is true then I see this as a silly simple to fix over sight. Also the one and only thing I miss from my WM6.1 phone is that you could set a new event such as a birthday and if you put the start date as the actual date it would add a number next to it equal to the amount that it had repeated. For example if I put my birthday 12/3/70 this year it would say "My birthday 40" I know its trivial to some but is very useful.