Ok this might be a very dumb post so i apolagise.

MSN Messenger uses xml logging now, doesn't it?  If so how about this.

say a conversation is going like this

Me> hey
Jack> Hiya how are you
Me> Fine, have you got Tonys mobile number?
Jack> sure it's 04989865476
Me> Cheers

can xml be smart enough to open up a tag like this <phonenumber></phonenumber>.  Where it would wait for characters to be inputted and then filter out the non alpha characters thus putting 04989865476 into the phonenumber tag, so when searching through logs for phonenumber it knows exactly what you mean.