Using Google Groups for user group mailing lists?

Atlanta PHP recently migrated to Google Groups (from our own hosted 
Mailman instance) for our mailing lists. I also found out that DC PHP 
recently moved to Google Groups, as well, and Hans (of NYPHP) mentioned 
to me that other groups have done the same and was wondering about the 
rationale for the moves.

What do you use for your mailing lists? Why? If you've moved your lists 
to something like Google Groups, why did you do so, and what did you 
move away from?

-- 
Ben Ramsey
Atlanta PHP
atlantaphp.org