Today, the Irvine, CA-based developer announced that it would be changing its free trial system to let players play as often as they want, for as long as they want, on as many characters as they want. The normal trial restrictions are still in place, of course: You can't go above level 20, and your ability to send in-game messages and use the in-game auction house is restricted (just in case, y'know, you're a gold farmer).
Still, being able to play up to level 20 on as many characters you want is a pretty good deal, especially since the newbie zones are arguably some of the game's best content following the Cataclysm expansion pack. Hell, you could stop at level 19, twink yourself out, and engage in low-level PvP for free as long as you wanted.