Ok, essentially those 3 FastTrack network apps share files via HTTP on a certain port (see link below for specifics). This means that if someone were to discover your IP and connect to it via HTTP on the FastTrack port (only possible if you are running one of the 3 FastTrack clients), they would be able to see a listing of all the files you have currently shared.
Fine and dandy, right? Wrong. All too many people unknowingly share the same directories where they store unencrypted passwords, bank info - what have you.
So basically, make sure that you only are sharing what you want to with M/K/G.
For more details, go to
http://arstechnica.com/ - they have a news item about this, with a link to more relevant sites.
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