I wrote a previous post about monster roles. This is a follow up to describe which roles the character classes would fall into.
Cleric: Controller (note this means they follow the monster role of Controller, not the player role called Controller). With the right powers, though, they can try to be somewhat like Soldiers or Dragons.
Fighter: Grappler, specifically a neutralizing grappler.
Paladin: A paladin who tries to defend the party is a Soldier (and a much better one than the average monster). A paladin who tries to trigger his challenge by running away from the opponent is more of a Skirmisher.
Ranger: A classic twin strike DPS ranger is a Brute or an Artillery, depending on his style. A ranger who avoids the pure DPS feats in favor of the mobility feats is a Skirmisher.
Rogue: The quintissential Flanker.
Warlock: The Warlock’s shadow walk is the only “pure Skirmisher” power the players have. In general, though, PC’s Skirmishers aren’t as devoted to that role as monsters are, so Warlocks can seem pretty close to Artillery.
Warlord: Pure Controller. A warlord can’t really do anything without trying to help his allies!
Wizard: Artillery, specifically area effect artillery.
None of the classes are inherently Dragons, but it is easy to make such a character if you want to (I quite enjoy making sword-wielding warlocks and such). It is also easy to make a Versatile character if you want to (such as dual blade/archer ranger). The new swordmage appears to work like a Paladin.