What is it?
Windows Messenger AKA MSN Messenger - msmsgs.exe

What does it do?
msmsgs.exe - This is Microsofts version of AIM or ICQ. Just like Internet Explorer they've been forcing it upon people for years being installed on your system by default. They hope that you will use their IM/Chat app instead of downloading and installing a seperate one. Below is a way to stop it from automatically starting up.

If you don't use Windows Messenger, you can disable it as follows: Start -> Programs -> Windows Messenger -> Tools -> Options -> Preferences. Uncheck "Run this program when Windows Starts

To fully remove the app you'll need to modify a windows file:

X:Windowsinfsysoc.inf (replace X with your windows drive)

Open it and look for:

msmsgs=msgrocm.dll,OcEntry,msmsgs.inf, hide ,7

Change that to this:

msmsgs=msgrocm.dll,OcEntry,msmsgs.inf,,7

Now under add/remove --> Windows Components you'll have the option to remove this ;)

More Info
More Info

Virus Precaution:
The original file from Microsoft gets placed in the Located at C:Program FilesMessengermsmsgs.exe . If you find it anywhere else then you should be suspicious for sure.

You'll want to keep an eye on this google search for any known viruses. At this time I have not found ANY viruses that run themselves using this filename. All of the results currently affect this file in some way, but do not actually run as this filename.