Well, I was wrong about this one. I'll be honest: last night, I came up with a really good explanation for her focus on the bill moving too quickly. As several people have noted (here's Matt Yglesias, here's Steve Benen, here's Josh Marshall), this seems to be a fairly preposterous basis on which to vote. If the health care bill was moving really quickly. Which, most people think, it isn't.
But then I thought of a seemingly clever explanation: she's setting herself up to vote against cloture, but for the bill. Aha!, I thought, that works. No one could really claim that an otherwise worthy bill should be opposed because it was moving too quickly, but "moving too quickly" is a perfect explanation for opposing cloture while still claiming to support the basic idea that health care reform is needed and that the present bill does that. If Snowe had decided for whatever reasons (whether it's home state politics, or pressure from Republicans in the Senate, or whatever) that she wanted to be a no/yes vote, then "moving too quickly" is the one public explanation that actually fits.
Unfortunately for my reputation for cleverness, however, it turns out she's just going to oppose the bill, apparently (although since I was sleepy and didn't post it, I suppose that I'd only get credit from myself if I had been right). In her statement, she does mention the CLASS act and the strengthened employer mandate compared to the Senate Finance bill she supported, plus a bunch of procedural gobbledygook, but really there's not much there for someone who really wants to support the bill. On the other hand, she does leave the door open to voting for the conference report.
It really is a puzzling reason for a vote on a major issue.