I just heard about a new free app "Multi-Touch for Gallery", it is a Gallery replacement that you can set to open with the normal Gallery link. It appears like a native Gallery replacement, but is really a redirect but has the same effect (you can change default behavior). Has pinch and Zoom and you can swipe thru all your photos. Not sure if this has been mentioned before, but thought it worthy. Does what is says even though the pinch an zoom is a little fast. Still a step in the right direction.