What is piece 4211642 from 10179 - UCE Millenium Falcon?
According to the LEGO customer service, this part is a "BUSH Ø7.84" (which is of no help whatsoever, as with most LEGO internal names) and has the design ID 6221. Unfortunately, there seems to be no official picture for it yet.

This design ID corresponds indeed to the part which Joel Cohen and BradC have identified; the element id of the same part in black (622126) as found by BradC follows the old convention design id + color id (26 being Black at LEGO). And this part at the LEGO customer service does have a big image which would clear all doubt if we had any left:



LDraw and Peeron know this part as 424 - Technic Handle. BrickLink does too but refers to 6221 as alternate item number. This happens often with parts which have no markings whatsoever and for which the official LEGO design ID wasn't known at the time the part was added to the LDraw library.

Why the inventory at both Peeron and BrickLink misses it is anyone's guess, but it's one of the biggest LEGO sets ever so it's bound to have mistakes. Although I see the list for Peeron has been provided by LEGO itself, so it's a bit weird. 

Is the part actually used somewhere? I don't have the strength to read the whole manual.