We previously used google groups but moved to Groupspaces. Groupspaces provides better information tracking. We add contact information, year joined, year graduating, and many more data points to each member. You can maintain one person and add them to multiple groups (design, programming, etc). Each group has a listserve email address (anyone can use to communicate with a sub team or the whole team). Groupspaces also supports very professional looking email newsletters. It does not seem to be a thriving company and I hope to change to
http://www.wildapricot.com/ as soon as the add list serve functionality (planned for September)
Google Groups is free, Groupspaces is more expensive, and WildApricot is considerably more, but includes many more features.
Our process starts with the team leaders planning meeting before one regular meeting each week. After announcements at the start of that meeting the email to parents and students is finalized with updates, key dates, and action items, and sent out.