One of the little conundrums in OpenAtrium (and I imagine in Spaces) is building static content for the space. (Or in OpenAtrium terms, getting a nice dashboard box to stay put, yet be customizable by group.)
There are countless ways of doing this, but I opted to create a CCK Textarea field in my group content type (named field_group_welcome_message) and turn on the PHP filter.
Bio in Brief: I spend a lot of time thinking about how to build collaboration tools in Drupal. Before that I noodled about with Java looking at long-term data preservation and geospatial data discovery.