According to Eklund (yes, yes, I know), it's not only a rumor but a confirmation (e5) that Tanguay has signed a contract with the Panthers.
There is no news elsewhere yet that I have seen, but keep an eye out. He was right on Koistinen and he was on with Tallon, so it.. might.. be possible..?
4:30 PM: Panthers interim GM Randy Sexton has told Steve Gorten of the Sun-Sentinel that the reports are 'false'
Meanwhile, Tanguay is listed at the NHLPA website as a member of the Montreal Canadiens again next season, set to earn $5.375M. I guess we'll see soon enough.