Helloooo Ian, Yep, they're part of the same Windows Live dumb little process to take over your entire computing experience. It's all part of MS secret plan to slowly infiltrate your need to keep in touch, whilst still keeping an eye on ALL of your computing habbits......(i.e. think big brother.....only privatized!) Windows Hotmail, Skydrive, Instant Messenger, are all linked together, as well as a bunch of other things that the folks in Redmond think that you'll need. (Fear not, I'm sucked in to the same vortex, as millions of us are) As to why this "annoys you for some unknown reason", I'm afraid I can't answer that one with just one visit to the couch.....however, if you'd like to deposit another 50¢ in the little tin cup, maybe we can discuss this further in depth...... ;-)
It's just part of the Microsoft world, and their is NOTHING we can do, (unless you can find a registry hack to void the icon altogether, which in this case, you might set off certain alarms, and I would then fear for your safe return to us! So please proceed cautiously!!!)