for those who are looking for nMP 6-core stock model, B&H has them in. Back in early Feb, after ordering within the first hour of them being online at Apple.com, i was still waiting and since a stock 6-core was what I was looking for, cancelled apple order and bought rom BH. They were great, free SW and overnight shipping. Just an FYI for those still in pain waiting. http://www.bhphotovideo.com/c/product/1021114-REG/apple_md878ll_a_mac_pro_desktop_computer.html
I got a 6c/16/256/d500 unit from MacMall last week. Noticed them on Thursday afternoon and had it in my hands on Friday! Great service! My last iMac came from B&H, they do great as well! Honestly, I think they pull from the same stock as they both seem to ship from Memphis!
Wow and it's $5 off Newegg may have these in stock as well. It's listed there as "special shipping." FWIW I ordered a quad core nMP from Newegg a couple weeks ago and it came in two days, but it wasn't "special shipping" at the time.
When B&H sells out, keep an eye on them. They are at least getting some in stock fairly regularly, including some non-stock configurations.