Hey, here's an idea that a few of us were ruminating about over Grifball:
I have Tezzeret, Agent of Bolas, and, say, Jace, the Mind Sculptor, and a Liquimetal Coating. I tap Liquimetal Coating to make Jace an artifact, and then use Tezzeret's -1 to make him a 5/5 artifact creature. Reading Tezz's effect, I don't think this would be very beneficial. It doesn't say anything about "in addition to its other types" like Liquimetal Coating does. I think, upon transformation, Jace would become a 5/5 artifact creature with none of his abilities intact.
EDIT: I'm reading on various internets that they DO retain their abilities, but they would take and receive combat damage as normal IN ADDITION TO Loyalty counters, so when their loyalty runs out, they explode as normal.
However, it can add another measure of protection to the relatively unprotected planeswalker if you were to, say, slap a whispersilk cloak on Robo-Jace or something.
I'm just trying to half-bake a janky idea involving Tezzeret turning Sorin Markov in to a robot, THEN using Captivating Vampire to make him an ACTUAL vampire instead of a fake one, slapping a Blade of the Bloodchief on him, and having him blast things with his +2. Or running Esper colors and making Venser an unblockable Infecty guy with Phyresis.