Kotti is on Google Groups and can be viewed on the web or be subscribed as a mailinglist.
Join the Kotti developers on IRC: we're on the channel #kotti on irc.freenode.net. Use your favorite IRC client or freenode's web client.
Sprints are an essential part of the Kotti community's culture, where we meet each other for 2-3 days in real life from time to time. Join us on IRC or the mailinglist if you want to sprint with us.
We also have a monthly "Kotti tuneup" which is also organized on IRC.