I get a little angry ever time I hear the "both parties are the same" line, especially as I think it is far less true than it was a few years ago, and for the right reasons.

An Obama win continues to build momentum in a vaguely leftward direction, by showing that the hard work the various left-leaning volunteer and fund-raising networks can have success.  Grassroots pressure for stronger and more outspoken candidates has resulted in a crop of much better House and Senate candidates, but a lot of them are not going to win without a solid win at the top of the ticket, and will have absolutely no chance to accomplish anything with a Republican president.  Not only does an Obama victory set up the chance for an even stronger progressive at the top of the ticket in 2016, but it also validates the work a lot of people have been putting into the Democratic party.

Further, the corporate money has been really leaning more and more towards the Republicans in recent years, and this really matters for the "both sides are controlled by the same rich donors" narrative.  Fact is, the Koch brothers are NOT donating to Democrats, ever, and thus when Democrats win despite their efforts they are in no way beholden to them.  A solid win for the Democrats in down-ticket races this cycle, despite Citizens United and despite the lopsided pro-Republican spending of the big money interests, can start to free up the Democrats from any need for subservience to those same interests.  Relating back to the first point, I'm guessing that one reason that this cycle has seen a distinctly progressive crop of candidates has been the shift of the big money to the right - there's less and less point in running as a business-friendly Conserva-Dem, because the people who back them have sunk their money into the other side.

In my opinion, the continued hold of Third Way neo-liberalism in the Democratic party is much more an issue of narrative capture than funding at the moment, but even that is weakening.  And every minor little victory that Obama and the Democrats have, and ever time a new government policy helps a few people here or there, that narrative is weakened a bit more.  As the original diarist pointed out, those little victories are happening in energy and transportation policy, they are starting to happen in health care, and they have even happened in financial regulation.  Those little victories can be built upon with momentum.