If you let Clementine leave Lee then all you see is Lee passing out (Turning?) so that can mean anything in the next season.
Also if you choose to make Clementine Shoot Lee then if you listen closely after Clementine makes the shot and the screen goes black you can actually hear Lee breathing in (Zombie Lee or regular Lee?)
http://www.youtube.com/watch?v=qrGur-Qli9Y&feature=plcp *Clip of the Ending*
And (Maybe im wrong on this one) if you look at where Clementine's aiming its at Lee but when the trigger is pulled and the shoot is fired it looks like it goes aside and misses Lee (looking from the angle).
Right now this could mean anything or nothing but i want too know what you guys think about this.
(Sorry for my bad English)