Amazing!!!!
I'm still testing this out, but I may have found the best Macbook doc available at this time - and it's from Microsoft!
Here it is...
http://www.microsoft.com/en-us/mobile/accessory/hd-500/
It's $99 from the MS store, so I bought one. It comes with a power supply and USB-C cable. It has three USB 2.0 ports (with they were 3.0), an HDMI port, and a Display Port. Don't know what version of HDMI or DP it supports?
Anyhow, I just plugged my 12" rMB into it, and it;s flawlessly driving a HD display, via the HDMI port. Now to scramble and see if I have a Displayport adapter sitting around, to see if it will drive my 2560 displays. also wondering whether it will support two displays?
It does appear to be charging, via the USC-C power adapter, though I'm not sure of the charging rate or voltage? More testing to be done, but this is a nice start.