A team at Vanderbilt University has been hard at work and has come up with a prosthetic arm whose characteristics are far closer to that of an actual human arm than anything else so far. The weight is pretty close to the same and its capacity for lifting and other tasks is pretty on par too.
I guess the biggest problem with battery powered arms was that in order for the arm to be able to lift anything it required a huge battery causing for a significant increase in weight making the bionic arm feel even more alien. This rocket-fuelled/steam-powered arm solves that problem by creating enough power on the fly to lift stuff and still managing to keep it all in a compact package.
The video is of Mr. Goldfarb, the leader of the project. They seem to be clipping along with this project, they have 30 million from DARPA so that should ease financial woes. The project started out using a cold gas, liquid nitrogen, to check for lots of things, and now have started testing with steam that gets heated to 450 degrees Farenheit.