Wow! This site is so informative.
I didn't know there were left handed peeps in the world.
Seriously though m8, that bit looks like it has just been stuck on but doesn't look like it would fit on the other side.
Pity, as, if they can do it with number pads on keyboards, there is no reason they couldn't make the stick interchangable. ?
Take note Razer, if you made a mouse similar to the G9 with interchangeable shells and the main body with touch sensative areas for the side buttons, all you would have to do is make right and left handed outer shells to be able to suit everyone.
The simplest ideas are the best ones and that one should be worth at least a £1,000,000 to you.