It's doubtful that Martina would be picked. I think Lisa will once again fill the role of doubles player and top singles reserve. Don't be surprised if the US fields much the same team for the semis as for the quarters.
I think we can probably rule out Serena, who may not be back to full strength by then. And if Lindsay hasn't had her surgery before the year-end Championships, she'll want to have it as soon as possible thereafter, so she can recover for Oz.
Monica probably won't be able to play, although if she's back on court by then, and King asks her, she will try. I think we can rule out Jen because of the clash between her and BJ.
That leaves two physical question marks as our lead players; Venus and Chanda. Both should be healthy well before Fed Cup, but will they be up for playing an extra week?
If only one of those two can play, I'd assume Meg would be the #2 singles player, in which case we'd need a strong backup. (Although Lisa's a good singles reserve, clay is her worst surface.)
If neither of them (V or C) can play, then it won't matter if we pick Martina, 'cause we're boned anyway.
I think the only way Martina is picked is if BJ had 2 of her "big 6" (Serena, Venus, Lindsay, Jen, Chanda, Monica) on board in complete health.