Cell phone service is coming to New York City's subways, which might seem like an arcane subject for us to cover, but check out the photo after the jump...

Toward the end of last week, the John Edwards campaign pulled off a bit of a technological coup — they got around the inherent limits of raising money via cell phone text message. But here's the rub: the tools they used may not work as well again for Edwards, or for anyone else for that matter.

Here's what happened. As Justin Oberman ably described on Friday: