You've got by far, I think, one of my favorite concepts in this competition. The detail you've put inside the body and with the pistons is very nice- though the colors are a bit too vibrant for me to really distinguish the detail and shadows etc…making it difficult to critique to any level. The main thing I don't like about this, though, is how you went about the wings. It is mechanical, yes, but not very creative and it doesn’t completely reflect the anatomy of the hummingbird the way I would personally like (all of this is simply IMHO, of course). I would create your hinges in respect to the
true anatomy of this animal. I would model them more after this. I would also set up a more complex rig for those wings, it just overall looks too basic- perhaps it is just the colors, though.
I really like this concept I just think you need to rethink your wings, I could see you doing much better things for them. If nothing else, I think adding some wires and/or pistons, hydraulics, etc. around the wings in some way. I just don’t see precisely how the wings would function. Good luck on this, I think you’ll do a bang-up job if you make those wings a bit more interesting to the eyes.
I look forward to seeing it progress.
[edit: I don't know how I missed your progress earlier...]