This article is well worth reading in its entirety if you're interested in 2016:
http://www.politico.com/news/stories/0912/80776.html?hp=f2Interesting tidbits from the article include:
-Biden decided not to make a breakfast appearance with the Iowa delegation as other 2016ers are because it would look unseemly for Obama's VP to be seen as looking past this election......but he's been meeting with smaller groups of Iowa politicos in other settings.
-Biden's fellow Delawarean "Gov. Jack Markell also may consider a White House run, according to a Democratic source."
-Is Villaraigosa also planning a 2016 run, even though he's only a mayor? "Villaraigosa is keynoting Iowa’s J-J Dinner this fall."
-Everyone agrees that no one is running harder for 2016 than O'Malley: