Intrade market currently gives Mitt Romney a 69% chance of winning--and gives Ron Paul a 30% chance. The only reporting on Maine has been that none of the candidates have been spending their resources on Maine, except for Paul. Paul's campaign believes he is stronger in caucus states, and lacking competition in Maine, hopes to pull out a win.
By its nature, Maine is a pro-Romney state: It is a Northeastern state and voted for Romney back in 2008. However, as we saw in Minnesota and Colorado earlier this week, that doesn't mean it's a lock for Romney. Since the Romney campaign is in "delegate mode" and concerned only with racking up delegates, it makes sense that they would skip the state. But because Maine will be the last state to vote prior to the important contests on February 28th (in Arizona and Michigan), it may contribute to or blunt certain media narratives.
The media is uncertain whether Rick Santorum's sweep of three states on Tuesday was a fluke, or whether Romney is going down in flames. It's also unclear whether Newt Gingrich's campaign is completely collapsing, with all of its support going over to Santorum. Maine may provide some hints, even though no one beside Paul is attempting to compete there.
If Romney loses the state, there will be some rumblings about his weakness. If he wins, it will be treated as a signal of his strength in the Northeast. If Paul wins the state, Maine may be written off as meaningless. Attention will also be paid to Santorum's and Gingrich's numbers. If Santorum does poorly, the media will begin grasping onto the idea that the regions are split among candidates (Romney in the Northeast/West, Gingrich in the South, Santorum in the Midwest). If Santorum does well, particularly if he does much better than Gingrich, it will be viewed as a sign of his emerging status as chief Anti-Romney.
It's not unrealistic to think Santorum could do better than expected. When other candidates surged during this primary season, they surged across the country at once. Santorum has not been vetted yet, and certainly hasn't been attacked in negative campaigning in Maine, so voters will assume for now that he has no real weaknesses.