Nice feature and developing nicely.
This is probably going to be my biggest incentive for me to start using MC properly for my Photos.
Few small suggestions for this upcoming hugely encouraging feature:
1. 'Preview' always spawns a new browser to preview each template for me - theres no quick way to see what the skin roughly looks like. How about having an image preview with each template folder able to contain a 'preview.jpg' image that is a screen shot that gets loaded on the actual 'Web Gallery Creator' page so as I'm flicking down the list I can get an instant preview of roughly what it looks like.
2. The html code for some of the templates could be improved (done better) - eg noire - why does it have a seperate page for each image when it could just use some simple JavaScript to change the main image viewed and any text to go with it. This would: A) save having hundreds of html pages. B) make it a lot more dynamic pages so you dont always just end up in a reset page with no idea of state or where in the list of thumbnails you were browsing.
3. An option to crop all thumbnails so they get shown as squares instead of their actual shape = prettier preview pages.
4. Maybe have a small little options page that goes with it that allows some basic config of the gallery you are about to create (just changing some CSS values) - ie: background colour, text color, font, a frame to use for the thumbnails, etc.
This is a really great feature and I hope you're planning to work on it and continue to improve it