Well that's pretty interesting, I'm open to the possibility that there's some sort of taste difference... but some other little experiments on the web:
http://www.monzy.com/?p=238 seem to show otherwise. I think mythbusters found otherwise, but then again that was with professional taste testers, I think Kari for instance didn't pick it... so there might be a difference, but it's one that requires a clever tongue. I can't find much of a consensus out there...
I think it'd also be interesting to try it mixed, since that's how most of us drink it. I mean if cheap shit vodka gives me the same experience as expensive stuff mixed, then unless I'm planning on doing some shots why would I buy the expensive brand?
I guess we'll have to create our own little experiment this weekend, should be fun