The topic of TSN/INN patents came up recently on another discussion forum that I frequent, and we ended up doing a little checking using Google’s patent search.
We only came upon one patent relating to TSN, but it’s an interesting one:
http://www.google.com/patents?vid=USPAT6692359&id=QfIQAAAAEBAJ
Looks like it was (and still is?) owned by AOL.