Per ESPN's Keith Law:
http://insider.espn.go.com/espn/blog/index?name=law_keith#20060818

Vernon Wells has told Blue Jays' management that he has no intention of signing a contract extension to stay in Toronto; he and his family would like to move closer to his home in Texas, and he has become increasingly disenchanted in Toronto as he has faced public criticism from general manager J.P. Ricciardi. It hasn't helped matters that the Blue Jays' clubhouse has become one of the least diverse in baseball, with Wells currently the only African-American player on Toronto's 25-man roster.
Wells has one year remaining on the five-year deal he signed in spring training of 2003 and will earn just $5.6 million in 2006, after which he'll be eligible for free agency entering his age-29 season.

Sources around baseball indicate the Blue Jays will explore trading Wells this winter rather than allow a repeat of the Carlos Delgado situation in 2004, when the team was unable to trade the impending free agent due to Delgado's blanket no-trade clause and thus ended up with nothing after Delgado left. While the Blue Jays could play out 2007 and take two draft picks for Wells, they're looking at Wells as the one chip they might be able to play into some help for their beleaguered rotation.

There will be no shortage of teams interested in Wells, a middle-of-the-order bat and plus defensive center fielder who'll hit the market in the middle of his offensive peak. Texas and Houston are likely to have interest because they might be able to sign him to an extension before he hits free agency, and neither team has a solid incumbent in center fielder.

However, Wells' destination in 2007 is going to come down to which team is willing to give up the most major league-ready talent in exchange for Wells. The Blue Jays are built to win now (what with the balloon payment coming due on A.J. Burnett, B.J. Ryan, Troy Glaus and Roy Halladay starting in 2008) and aren't going to deal an MVP-caliber player like Wells for guys in Z-ball. It's a trade that can make or break the immediate future of the Blue Jays.