With the conclusion of the World Series, players can now file for free agency. Placido Polanco, Adam Everett, Fernando Rodney, Aubrey Huff, and Jarrod Washburn did so Thursday. The only player eligible for free agency who didn't file right away was Brandon Lyon, but according to Jason Beck, there's apparently nothing to read into that.
The Tigers can negotiate exclusively with their free agents until November 20.
One more note from Beck's post on the Tigers' free agents: Polanco qualified as a Type A free agent, meaning if Detroit offers him arbitration and he signs with another team, they'll receive two draft picks. One would be from the team that signs Polanco (possibly a first-round pick, unless the team has one of the top 15 selections in the first round, which are protected), along with a supplemental pick between the first and second rounds.
Rodney and Lyon are Type B free agents, which would yield a supplemental draft pick if they're offered arbitration.
(Here's an explanation of the free agent compensation rules from ESPN.com's Keith Law. It's an Insider article, however. MLB Trade Rumors also explains the process.)