Hey there,
Perhaps this might be covered in an upcoming "custom fields" but I wanted to make a point that allowing a group to add a photo in addition to their avatar would be a very nice feature.  Often, smaller groups and clubs might not have a logo or symbol for an avatar, but a group photo is pretty easy to take.  Having both would be terrific.

If you are planning to release custom fields for groups in the near future, then perhaps image could be a file type which would be perfectly usable in this concept.

Thanks!

Edit:  I should mention that this should be independent from the group photo gallery functionality.