For a long time, people have been triggering remote off camera flashes using various tools but one of the weaknesses has been the inability to get the full advantages of TTL. About 2 years ago, Radio Popper made a nice system but it forced one to have an on camera flash and then velcro or tape this ugly transmitter to the flash.
Definitely not for me.
Last year Pocket Wizard made the MiniTT1 and FlexTT5 for Canon and IMHO the results were disastrous. Range issues, stability, incompatibility, reliability and even some cases of flashes being severely damaged were some of the results.
In the meantime, Nikon users were left out in the cold, but as a Nikon user, I am glad we do not have to go through all these frustrating and maddening teething pains.
Though far from perfect, the recently released Nikon units do a pretty good job. Europe and Canada were the first places to start to receive them, with the USA getting their first shipments in mid January.
Mine came in on December 31st and I spent a few hours on New Years day playing with them and doing some tests.
If you would like to read the results of my ramblings about it, you can read about it HERE.