These threads remind me of my sportbike days.
Everyone wanted to get new pipes, bore their cylinders, add special high flow air filters, special Z rated tires, lighter seats, carbon fiber cupholders, all to get that few % of performance...
when they couldn't even ride the stock bike at it's capacity, let alone a modded one.
Few of us here use ALL the power of the current mac pro. Waiting for an update is really not necessary, especially when there is no update announced and no way of know when it will happen. The mac is going to perform either way. I have never seen this phenomenon of "waiting" for the next big thing anywhere else, mac users are quite anal and fanatical about this.
So, you can wait for carbon fiber cupholders, or realize that with a current mac pro, or a new Death Star, you probably are going to do the EXACT same stuff at the EXACT same speeds. This isn't the jump from the G5 to Intel, it's going to be an extra cupholder and some pinstripes.
For all you know, a meteor will strike southern california, and then you'll never get a mac.