While high-profile Republicans and Democrats are enjoying the media spotlight for a chance at an '08 nomination to their respective parties there are some things going on you don't know about.
I've often been asked why Libertarians have such a hard time getting elected to national office or don't have much financial support. One big reason is that Republicans and Democrats do not have to play by the same rules.
Currently Libertarians are working to collect a total of 787,945 signatures meeting different state conditions to get ballot access in every state of the nation. The LP is in court in two states whose laws have made it nearly impossible to get ballot access at all for anyone who is not a Republican or Democrat. In many states where the ballot access requirements are met it is against the law for a candidate to identify himself as anything but a Republican, Democrat, or Independent. I remember Harry Browne discussing how when he voted for himself in his home state of Tennessee he appeared next to the Socialist Workers party candidate and they were both listed as Independents.
Even with these sometimes impossible odds the Libertarian party has been the only third party to put a Presidential Candidate on the ballot in all 50 states (plus DC) in the last four general elections. (except for Oklahoma in '04 because changes in their laws made it impossible to get ballot access unless you had an R or a D by your name.)
So while the media is gawking at Obama and Hillary and following Romney and Guliani around, know that thousands of Libertarians are spending tens of thousands on court fees and signature gathering simply to get on the same ballot that Republicans and Democrats get on for free.