Nothing shows up in my messages folder. It looks like it should go with my YIM, but it wasn't logged on when this arrived. I logged into it to look anyway, just to be sure, and there was nothing. It played the sound that I have associated with my Ubertwitter.
I've not added any apps particularly recently, but I did get a new phone on Monday. I've gone through my apps, and I can't find anything that would have put it there. I restarted my phone, and it's still there. I'm baffled, and will probably feel like a complete doofus once somebody tells me what it is.