The primary election for Republicans is on May 27th. There is no voter registration or party affiliation required to participate in the caucus, just a signed pledge that you will be voting in that county in the general election. More information
here.
The Republicans tried and failed to gain closed primaries after a number of people 'crossed over' to vote for Bill Sali last time, underestimating the willingness of Idahoans to vote for
absolute idiots.
I think elections in general are conducted pretty well here, I have never experienced a long wait or any difficulty voting. I voted early last time and may again. You can register at the polls on election day, but I would do so earlier just to avoid another line.
You're probably right about Mittens gaining the Repub nod. Idaho has the second highest Mormon population after Utah, and that is sure to be a big factor in his favor. On the Democratic side, only the
Obama supporters seem to have any presence here. They look quite motivated and may give him a runaway if nothing big happens for Edwards or Clinton over the next month.
I'm looking forward to caucusing for John Edwards. This will be my first time, so it should be interesting.