Pollster.com

This is why I have doubts about Obama's 50-state strategy. Sure, it could help him with down-ticket pickups in conservative states, but I can't help but wonder if money spent in Tennessee is better spent in hard-fought swing states.

@josephj:
That's a pretty common worry, and Obama's gamble. Still, there's only so much money can do in swing-states, and I am pretty sure the Obama campaign will take care of that.
The good thing is, Obama is building up the Democratic Party. A recent report talked about Texas being just 5 seats away from a Democratic legislature - which will help in redistricting and thus future electoral gains.

http://kos.dailykos.com/storyonly/2008/6/25/125521/563/299/541772

Also remember that having a 50-state strategy does not mean that he will compete equally hard in all 50 states. Take a look at the Politico article from earlier this week--it's clear that Obama is focusing his offense on 14 key swing states won by Bush in 2004 (with TN not being one of them). He will no doubt send staff to TN and set up offices, but I wouldn't expect to see much in the way of advertising.