Need for "Shout Out" Functionality

I would like a mechanism to send mini requests/questions to fellows that is by default private to a group and that has a short expiration. I think of it as a hybrid between IM, forum and mailing list. I think Drupal has it already:

http://drupal.org/node/10720 (there's a link here to a site that has it)

The idea is that it's not crucial for everyone to see it, but in case you happen to be on the site and see it, you can react to it.  It's very informal but potentially reaches all of us.  Times in which I would have used such a shoutout:

• Asking for carpooling for TechAwards
• Asking if any of you are going to the info session on ME206 (Entrepreneurial Design for Extreme Affordability) and if any are interested in taking the class
• Letting all know that I'll be in Rio tomorrow so if anyone wants to send a package to someone down there, I could pick it up today
• Anyone up for coffee/lunch now?
• Just heard of a cool seminar coming up later on today.  Who wants to go?  Here's the URL:.....
• Going to SF now, anyone wants a ride?

Things like this.  I guess they are more social in nature so they don't deserve Announcement status, nor do they need to permanently exist.  They usually need immediate attention or otherwise they are of no value anymore, so if you happen to see them right there and then, you can react to them, but if not, you would not want them filling up your mailbox, which is what would happen if you did this via the mailing list.

Would any of you see any use for this?  I would.