Welcome to politics - Clinton style. Obama's campaign manager:

“We currently have reports of over 200 separate incidents of trouble at caucus sites, including doors being closed up to thirty minutes early, registration forms running out so people were turned away, and ID being requested and checked in a non-uniform fashion. This is in addition to the Clinton campaign’s efforts to confuse voters and call into question the at-large caucus sites which clearly had an affect on turnout at these locations. These kinds of Clinton campaign tactics were part of an entire week’s worth of false, divisive, attacks designed to mislead caucus-goers and discredit the caucus itself."

For all you doubters out there, all I can do is tell you what I directly experienced, and heard firsthand from other volunteers at the campaign office. As further corroboration, the Obama hotline to report irregularities was busy for a full ten minutes.

At least two reports of Clinton operatives telling the uncommitteds and Edwards supporters, once their numbers were deemed not viable, that they had to leave. Whether these tactics succeeded or not, I do not know. Obviously, the Clinton campaign knew that voters not already in her camp were unlikely to join her camp (I know from my own experience that I convinced many more undecideds than my opponent Hillary operative), so they attempted to suppress their vote.

A few reports of probable out-of-state Clinton operatives being counted among the voters--though since checking ID is illegal, and other Hillary operatives from in-state would vouch for them, it's impossible to say.