Hi Alison,
On commonsinabox.org, to enable GD bbPress Attachments in BuddyPress groups, you need to navigate to the WP admin dashboard.
Next, navigate to “Forums > Attachments”. Find the “JavaScript and CSS Settings” header and check off every checkbox in this area.
Save and you should be able to add attachments to forum posts.
Perhaps we should start a wiki on the site to compile all these useful tips!
What Matt mentions is something that is in development and we don’t have a specific timeline ready for that yet.