CNN Reports that Frontier Flight 297 aborted landing due to a Key Lime charter on the runway.
With the bad weather at the time, it’s good that the pilots saw the smaller plane in time.
This is an interesting table showing the number of runway incursions in the past two years. It’s more than I was expecting:
http://www.faa.gov/runwaysafety/data/ri_tot.cfm?fy1=2006&fy2=2005
And for those who don’t know what the abbreviations mean, I’m nice enough to include this page that explains all the meanings (it’s on page 14): 
And it’s cool that the track shows the go around.
Cheers
Some good links in this discussion