Scout
I have a player playing a Scout in a campaign I'm running, and I've been pleased with how he's performed. The skirmish is a cool addition, and works great up until at least 10th level. The 10' movement, typically works in the favor of the Scout's tactics (firing from a bow), and consistently finding tactically advantageous positions to fire from.
I'm a little surprised that nobody's mentioned the really terrific component of the Scout that we've seen in our campaign. That is that they are great...well, SCOUTS! The scout from our party is TERRIFIC at hiding, moving silent, spotting, listening, and searcing for traps, and has a good init bonus. He has consistently put the party in a better position throughout the campaign (preventing surprise, sometimes granting the party surprise). It's also resulted in some funny instances, such as last night, of the Scout high-tailing it from 30' in front of the party to the back of the party). The Scout's combat effectiveness starts to take a real hit above 10th level. Fighting more creatures immune to sneak, and therefore skirmish, really limits his effectiveness (such as undead), and creatures like constructs that have DR in addition to immunity to crits, render them almost useless in a combat. Finally, giving up the second and third attack for the additional skirmish damage will start to take a toll at these levels as well. The ability to camoflage was VERY well used by the player in my group, as well, again with the whole "scouting" angle, and getting access to information that others wouldn't simply be unable to achieve easily. There is another rogue (actually a ninja) in the party who can disable traps, so that hasn't been a problem. If there weren't, and our party was more typical of a four person group, the scout would have HAD to invest at least a level in rogue to build up the disable device. A bit of a hassle.
The Scout in my present campaign has taken a level of sorcerer and is looking to go down an arcane archer path, which looks like it could be interesting.