Whether or not Percy Harvin is ultimately traded, the news that broke this morning can only be bad news for the Vikings, and thus good news for the Bears.
Harvin has reportedly requested a trade from the Vikings, who went 3-13 last season. Early speculation is that the Vikings aren't likely to grant his request; he's a 24-year-old budding star and the kind of player they would want to build around, and they're terribly thin at receiver. But Harvin's request is likely to produce one of two outcomes: either he'll be dealt, or he'll be unhappy and turn into a problem. Neither is something the Bears will mind very much.
Assuming the Vikings don't deal Harvin within the division (and he would be frigtening lining up opposite Calvin Johnson in Detroit), option one removes one of the most dangerous players in the NFC North from it. Along with Adrian Peterson, Harvin is one of the two Vikings of whom opponents really have to be wary. His catch totals have increased in each of his three seasons, from 60 as a rookie to 87 last season — a fairly remarkable total, given how bad the Vikings were at quarterback. He's also got four career return touchdowns.
With Harvin gone, the Bears' already high likelihood of picking up two wins against the Vikings this season will be even higher. I don't know what he'd bring back in a trade, but it's not likely to be close comparable value in terms of a big-play threat. Minnesota isn't going anywhere in 2012 anyway, so a trade would likely be for a piece or pieces that will help in the future.
If Harvin pouts his way for the 2012 season as the Vikings refuse to deal him, that could have almost as adverse effect on them as his absence. Christian Ponder and the Vikings passing game figured to struggle even when we expected Harvin to be himself. If he's holding out of training camp, not finishing routes and/or being a distraction, their development and effectiveness will suffer.
I'm getting way ahead of myself with a lot of this speculation. Who knows, maybe Harvin will backtrack, be a good soldier and have a big season. But I can't imagine the Vikings are very happy with his request, nor with it going public.