Looks a lot like a microphone. Actually, it looks even more like a trash can, almost identical to one I had from IKEA a few years ago.
The idea of an all round perforation isn't bad though, as it could be used to pull in more air, but I think the thermal core thing covers the new Mac Pro pretty well.
I actually really like the new Mac Pro design, though I actually wish it were more black than shiny; it looks awesome on the Mac Pro page, but when you see it in real-world settings I'm actually not as keen. Still looks good, but it's going to depend a lot on what you put around it.