As the second book of a trilogy, Catching Fire is an apt name--especially considering the kind of frenzy which surrounded Suzanne Collins's first book in the series, The Hunger Games. Catching Fire implies something has begun but is not yet completed (which suits the series), but it also implies something to come (which suits this novel).
More than anything, though, this novel prepares the way for the conflagration to come in the third book in the trilogy. The people of Panem are hoping for a change, are ready for a change, and they get a sense that this could happen in Catching Fire. All they need is a spark, and it comes in the form of Katniss Everdeen.
At the beginning of the story, President Snow says this about Kat:
"Katniss Everdeen, the girl who was on fire, you have provided a spark that, left unattended, may grow to an inferno that destroys Panem."
As if that were not enough, Collins titles the first section of this novel Catching Fire "The Spark," indicating that Katniss Everdeen is the spark (perhaps unwittingly and even unwillingly) which will lead to the coming inferno (revolution) which will in turn lead to the final book in the series, Mockingjay.
Catching Fire is the perfect title for this novel both for literal and metaphorical reasons.