Pix: Make a Google search on the net, and you'll find some, like here:
http://www.airliners.net/open.file/1027446/M/%5D.
There is also a Flight International article around, I'm too lazy to search for it. There it's explained that there are 2 different shapes, one similar to A330, one like on the BBJ.
The essays are done together with JetBlue.
I have the impression that JetBlue is looking for better fuel numbers, because those shapes are rather for better cruise performance, while the conventional A320 wingtip fence is optimized for take offs and landings. That's why A380 has a similar shaped wingtip fence (for less wakes).
At least that's my personal analysis of the public information.
hth,
Dani