D/D nowadays means you’re going to be running a Condition setup. It falls behind D/P in Power setups.
Essentially, run for a lot of Condition damage, and spam the hell out of skill #3.
^ Note that this only applies to PvP.
In PvE, you can run with the build linked below:
http://metabattle.com/wiki/Build:Thief_-_D/D_S/P_Shortbow
I’ve also heard of people still using D/D in WvW, but I don’t really mess around in WvW much anymore, so I can’t say if that’s really very worthwhile.
@ AChanceOfReign: The reason is because people are running a DA/Tr/DD condi build in PvP that revolves around spamming dodges and death blossom to constantly evade and condi bomb enemies. It’s a very easy to play build which is relatively effective in 1 v 1 scenarios, but I wouldn’t recommend it for higher tier gameplay.