Update January 22, 2006:  During December, virus writers used a social engineering trick to lure users into loading a virus onto their PCs.  They were offered a new MSN version 8 which did not exist at the time.  

Microsoft has now released MSN beta 8 and this update to the post is to confirm that invitations directly from Microsoft are legitimate.  While the Virkel.F worm did not spread extensively, users should always verify they are downloading from Microsoft's website.  Please be careful and ensure you are downloading from Microsoft's site, rather than the spoofed one used by this virus.

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  A new MSN "beta" is being offered to lure folks into infecting their existing PCs and MSN environment.  As a best practice, never accept software updates or products by email.  As an example, Microsoft does not distribute any software by email.

Virkel.F: Spoofed as an MSN Messenger beta 8 download

QUOTE: There is no MSN Messenger 8. Not yet anyway.However, there's a new virus going around pretending to be "MSN Messenger 8 Working BETA".  There's two ways to catch it. First, by downloading it from a fake site where it has been supposedly "leaked" ...