In Texas, Rasmussen offers a little bit of a tease to the Democrats. Barack Obama trails by 5 points against John McCain, while Hillary Clinton trails by 6.
Texas now appears on the Swing State List of both Democrats, although our swing state analysis does not account for the amount of resources required -- and in politics, like so much else in Texas, if you're going to invest in Texas, you had better be prepared to do it big.
My hunch in that an investment in Texas would be a bit quixotic for either Democrat -- although for Obama I think you can make a case that he's just as likely to win Texas as Florida, which is more Democratic but also much older.
Or, you could try and appeal to Texans through your VP selection: Bill Richardson would make an interesting choice.