using the Birthday Reminder Gadget you can share,search and get reminder.

First have a look on how to install extensions on Google wave here

1.  Use this url as manifest url: http://www.voizle.com/BirthDayInstaller.xml

2. Click Install

3. Click Confirm

4. Click Done on the Wave

5. Add the recipients and they can share their birthdays if they think so :)