Abyssal beat me to most of it. Skill challenges and extended skill rolls are the exact same thing. If you've been using multiple checks in sequence to determine success or failure, you've basically been doing Skill Challenges, just without the name. A few things challenges help do are:

- Get everyone involved. When you say "roll initiative" ears perk up. Players that would rather sit the non-combat stuff out have a reason to get into things and try to make stuff happen.

- Codifies things. Rather than "roll until the GM is satisfied" the skill challenge has a clearly defined start and end point.

- Negates pixel bitching. Things are set up in a way that there are several skills that are automatically capable of solving the dilemma at hand, and the GM is strongly encouraged to allow damn near anything else. There is little to no chance of flailing around hoping to hit on the one perfect solution that the GM is waiting on.

- Codifies difficulty vs. reward. It's a lot easier to decid how much XP that audience with a king should be worth if you can look at the underlying numbers and say "ok, complexity 3, two levels higher than the party."

- Makes it more likely that standard dungeon crawls where you kick in repeated doors, kills repetitive monsters, and take their shiny things won't be all there is. With a system in place for generating noncombat encounters, it becomes more probably that they'll appear in a game, and in a way that will engage the most number of characters (as opposed to triggering the Decker Effect).

None of those things requires skill challenges. and its likely that there isn't a group alive that has all of those problems. But challenges offer a simple solution that the new gamer can easily wrap his head around and put into play.

On my reckoning, the key innovation in 4E skill challenges is to let players pick the skills they are using. It's not that they couldn't do that in D&D before, but they'd have to do it in a less direct way (meaning, egging on your DM to make you do one skill check rather than another). In 4E, the DM confronts the players with a situation which is more generic than warranting just one specific skill check and the players are actually free to pick the skills they're using. The 4E DMG specifically recommends such "creative" uses of skills in a skill challenge, though it doesn't (in my estimate) reward it sufficiently.

I find this the only interesting tidbit about skill challenges. "Roll initiative" is gone with the errata (which really beats the point of much of the subsystem as written), and prolonged skill checks were treated equally well in 3.5 (Unearthed Arcana). But the innovation I'm talking about didn't hit d20 before Mearls wrote Iron Heroes and Book of Iron Might. It's player empowerment in that it's no longer the DM's exclusive domain to translate in-game talk ("I want to jump") into game-mechanical terms ("Do a jump check with DC x") (a thing that quickly gets less trivial than in the example I just volunteered). What I like more about Mearls' earlier stuff is that the players can not only select which skill they are using but also assign their own DCs or voluntary penalties thereon (cf. Power Attack for a related mechanism) to gain extra in-game advantages negotiated with the DM (e.g. "If I manage the jump check DC 15 I can go all the way to ...."). That aspect isn't translatable into a 4E skill challenge where the outcome is all but pre-arranged by the DM/module.

So me, I pick the Iron Might/Iron Heroes skill use in the stunt system therein any day over 4E. That said, all you'd have to do in 4E is to write off the skill challenge subsystem and instead give the table that's on p42 of the DMG (and reprinted in the DM screen) to the players and let THEM have the fun with it. You'd also need to expand the range of potential in-game rewards because, frankly, even in combat players want to do more than just deal damage (shift/push/pull effects come to mind).

Thanks, guys. I think I get it now. I've got to read the book again - I haven't read it since a little before it came out, I don't think - but I think the reason it's alien to me is that we've been basically doing this all along, just without the codification of it, which with our very freeform group, we just haven't needed. I think it's just a style thing, where it's just not necessarily appropriate for certain groups, which is fine because then you, you know, just don't have to use it.

I'll bet this makes writing modules easier, too: rather than the GM having to figure out, "Uh, I don't know, could they use Diplomacy in some wacky way to solve this problem?" the module can already have the answer to that problem, written down with a nice convenient DC.