Phil,
Wanted to circle back on this post. We just implemented birthdays in the JomSocial profile plugin for the upcoming release. It was much, much simpler than we anticipated since we already supported "Date" fields from JomSocial. Feel free to make the 2 minor changes below, test, and let us know how it goes!
Edit the /plugins/jfbcprofiles/jomsocial.php file. Around line 343, change:
to:
if ($type == "date" || $type == "birthdate")
And around line 450, change:
$query = 'SELECT * FROM #__community_fields WHERE type="text" OR type="textarea" OR type="date" ORDER BY ordering';
to:
$query = 'SELECT * FROM #__community_fields WHERE type="text" OR type="textarea" OR type="date" OR type="birthdate" ORDER BY ordering';
Let us know how that goes and if you run into any issues. Again, this will be in the 4.2 release, coming out later this month.
Thanks,
Alex