currently working on the Battlefield Play4Free microtransaction-based shooter, has posted some information on the official blog about how the game's class customization system will work. Rather than just choosing to play as a Recon, Medic, Assault or Engineer character, each player will get to fill out two different ability trees: one powering up "Equipment Expertise" (which allows your equipment to be stronger and more versatile) and one working with "Combat Expertise" (which adds versatility regardless of equipment).
In other words, one Recon player can spec Equipment and take down targets from long range, while another can go Combat, and actually explore the battlefield, finding and flanking targets as needed. Both, says Clarke, should be valid ways to play, but the plan is that choosing Engineer won't necessarily lock you into one specific playstyle.
It's an interesting take on designing and creating a character built for an online shooter like this. Battlefield Play4Free is still in closed beta, though EA is taking registrations right now.