Finally, we'll get a bunch of people decrying the existence of big money in politics, and yes, that is obviously a problem. But what we're seeing with these numbers, especially if small donors are a big part of that, is an unprecedented level of excitement and engagement by regular people in their political process.
I don't really think presidential campaigns cost all that much money. This is a big country and a national campaign requires a decent staff, a lot of travel, and, yes, television advertising. Add up what it costs to employ even a modest staff in dozens of states for a sustained period and you've already gotten to a pretty big number.
The issue isn't how much it costs, but the extent to which fundraising relies on big donors and big donor networks. Those aren't going away, but the more campaigns can expand their fundraising by increasing their share of small donors the less the "big money" problem is actually a problem.
...adding, there's some discussion over at mydd about whether all money raised online is "netroots" money or something else. Obviously it depends on what you think of as "netroots." A definition would certainly include a huge number of people who had never heard of the Great Orange Satan or the Baby Blue Idiot, but I don't think it's correct to see every dollar raised as the consequence of people being engaged with politics online in any form. Some chunk of it is no doubt simply from people who would otherwise write a check and send it in the mail in response to a direct mail solicitation, given that people are increasingly likely to do such transactions online. That is, it's basically just a technological change which doesn't necessarily involve people who are otherwise actively engaged in politics on the internet.
...adding, again, that somewhat paradoxically making campaigns be more expensive might actually force them to engage in activities designed to court low money voters. There's a finite pool of people who would even consider giving the legal maximum, and once you run out of them you need a new strategy. Washington Wankers thought it was scandalous when Obama dared to suggest that people at his rally buy into his campaign with a small donation, but I'd rather candidates spend their time holding large campaign rallies and collecting $20,000 bucks a bit at a time than having a lunch meeting with a small group of law partners to collect the same. And some of those rally attendees might be motivated to volunteer, as well.