Mailing lists for both the hData and L32 specifications are hosted by google groups. The groups are open to the public so anyone can join the lists and take part in the discussions.

hData general discussions list - http://groups.google.com/group/hdata-general

hData development discussions list - http://groups.google.com/group/hdata-dev

L32 development discussions list - http://groups.google.com/group/l32-dev/