Totally. This fits into the broader scheme of "inviting" people to events...I envision having some sort of checkbox or something when you create the event that will be along the lines of notifying or inviting the people within the groups that are associated with it. Then, it would send all the members a messages (and optional email) with the event details and a couple buttons to give their RSVP. I suppose that updating the event would be able to send messages to alert everyone of the changed details as well.

I was also wondering if it would be beneficial to invite individual people to an event rather than whole groups. The reason I ask is for situation like my church's music team. From week to week the members of the team fluctuate - there's never really a set "band" per se. While we could certainly set up one-off groups for each week, or perhaps just have a "Next Band" group that gets its membership edited every week...or perhaps you could just add a few individual people as attendees or invitees or something like that...I haven't thought it all the way through yet, but it seems like it could be useful for events that are more focused and variable like this. What do you think?

I think the individual select and communicate is a good option. It would be great for sending a PM/Email as well as invite to events. If I have to add them to a group to send a message then I am forced to add an unnecessary step to communicate. If I can add to group to enhance communication and make it easier then groups make sense. I like options. 8-)