Google Apps Team Edition is a new permutation of Google Apps (something I have been using a fair amount during the past couple of months) designed for collaborative projects.
You need to register using a work or school e-mail address (I am not sure how broadly they define groups for this – could a non-profit, volunteer organization use this service?) and then you get to use Google Docs, Calendar, Talk and Start Page as a group, customized to your needs.
from Official Google Blog
Added later: ars technica has an interesting take on how this service is enabling end users to bypass their IT departments
