You can contact the team in several ways:
The best way to contact us is through the mailing list, the address is ubuntu-sugarteam AT lists DOT ubuntu DOT com. You can also join the mailing list at http://lists.ubuntu.com/mailman/listinfo/Ubuntu-sugarteam.
We can also be found on IRC, on the Freenode server irc.freenode.net at #ubuntu-sugarteam.
Contact the Sugar Labs development team if you are interested in participating.