The link shows up on messenger telling you your friend has a certain number of photos up, and you have to share your login details to view them.
DON"T login. and if you do.. change your password on Hotmail/MSN to something very different immediately...
See the link for more details about how the scam works. the actual url of the scam is my cannon photos .com or similar. watch out for it.
http://handytechtips.blogspot.com/2009/08/i-was-nearly-caught-by-this-msn.html