I don't know, but since this is a board, I'll add my .02 cents worth.
Well warrantees are only as good as how someone will honour them. First question is does the warrantee apply to your situation? Do they explicitly state that wheels are covered? (by the way, is it the hub, or has the axle broken? Reason I ask is because an axle might be a relatively quick repair) I'm not saying this is the case, but usually they only cover against a manufacturer's defect and if you, say, dropped the bike fully submerged into a puddle of grimy mud for an hour, I can see them balking and saying it wasn't a manufacturer's defect. However, from what you posted, it would seem that 7 months of use, even assuming a 1000 miles a month is not good enough, certainly from my perspective. Assuming your bike wasn't abused, let's hope BikesDirect will step up to the plate here -but the question would be how long will this take?
If you are willing to wait and possibly be aggravated by sending annoying emails asking when it will be resolved -or just do not have enough money to replace the hub or buy a new wheel, I'd say keep waiting, emailing, writing, calling and see this thing through to a conclusion. However, if you need your bike, really like riding, and can afford it, just go out and buy a new wheel or hub and have it laced it up -in the meantime you can always follow up with BikesDirect for a resolution. You might also have to ask yourself if the time you might need to put in to obtain a resolution is worth it as well -and who knows, maybe BikeDirect get back to you within 24 hours anyway. If you don't like your wheelset this of course could be the prime time to buy a new wheelset (especially as a wheelset usually isn't that much more than a single wheel.)
I'm sure somebody will post that had you bought from an LBS you wouldn't have this issue of replacement, but then again, I think BikesDirect offers alot for the money, and even with a new wheel I'd be guessing you'll still be ahead in the money game. Anyway good luck with whatever you do!