Senator Craig Thomas (R-WY) died Monday. It was not unexpected, but it does open up some interesting possibilities.
Well, no it doesn't.
In most states, the governor gets to choose a new Senator who serves until the next election. Since Wyoming has a Democratic governor, this would result in Democrats picking up a seat in the Senate.
Except ... under Wyoming law, since Thomas was a Republican, the Republicans get to put together a list of three candidates, from which the governor has to choose one.
Oh well.