For me a playmaker has to do more than just get forward with the ball.
He has to run a game. Dictate the flow of play and control a game.
Scholes, Fabregas, Silva, Modric, VDV are the ones I would mention from England. Also to some degree Carrick can be this type of player.
Other then that the likes of Xavi, Alonso, Banega, Pizarro all stand out for me.
Not that I would offer this as the definitive way of breaking down playmakers, but it seems like the term should cover at least two types of players.
A lot people in the thread are focusing on attacking midfielders, like Cesc, Oezil, Nasri, etc. That's what I think of first, too: someone who plays up around the box, makes that final pass (or the infamous "pre-assist") and will chip in with some goals as well. A lot of them are almost hybrid midfielders-supporting strikers in the new formations. Kaka was that before he went off the boil. VDV is like that for Tottnumb. That's kind of how I saw Rooney before he was moved up last season to be the target man (and where I still wonder if he's at his most world-classy). Those are all different players, and including Rooney especially, shows that it's hard to draw a firm dividing line.
I would separate out as an entirely different class of player the likes of Pirlo and Alonso and (yeah, I'm pushing this one now) Huddlestone. These folks have been mentioned in the thread too, but less often. I think it's fair to call them playmakers -- why not? -- but a slightly more descriptive term would be something like "midfield general." They hang back, dictate the flow and tempo of the game, manage the team shape. They're certainly capable of playing up around the box and finding the killer pass, but they generally don't, often cause they have someone (say, Kaka for Pirlo or Iniesta for Xavi) who does the work upfield. Folks have suggested Roy Keane as a playmaker. I agree, on the midfield general side of the equation. Because he plays between Huddlestone and VDV, Modric is the best example I can think of a player who is both "advanced playmaker" and "midfield general." Really, I can't say enough about the spurs midfield. Really impressed by their shape.
Finally, I think we might have gotten a little off-track by focusing on individual players (or types of players). It might make sense to look at team tactics first, and see that as the impetus behind multiple playmakers. And here I want to address the OP's question that hasn't gotten much attention yet. With the shift from two strikers up front to a central striker (sometimes even a false nine, who is very much a playmaker), surrounded by flank forwards and attacking midfielders, players' roles have changed. So a player who would once (say, 7 years ago?) have not been seen as a playmaker, now is. Team tactics demand it. The team I know best illustrates this well. Arsenal's first choice midfield and attack is probably:
Wilshere
Song Cesc
Nasri RVP Arshavin -- They all work as playmakers. But this is obviously not just Arsenal. I see Bale and Lennon as playmakers. Madrid and Barca are full of them too, etc. etc.
