Current tracked tickets for Orbot can be found here:
https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=new&status=reopened&group=component&component=Orbot&order=priority

If you would like to join the project, we have some ideas for volunteering here:
http://www.torproject.org/getinvolved/volunteer.html.en#project-orbot

You can find us in IRC on FREENODE or OFTC in the #guardianproject and #tor-dev channels