I have partially created my first site with zenphoto and it works perfectly. I also submitted it to Google before 3 weeks and now Google has indexed around 450 URLs of my site (found using Site: command). Most of them are pages of individual images. However, seems like still Google hasn't indexed any image of my website because when i go to Google image search and type "site:www.mydomainname.com" (This is not my actual domain), it returned 0 results. What may be the reason for that?. This is very important for me since my website is a photo-based site and i expect significant traffic from search engines.
Can anyone give me some suggestions to solve this problem?
Thanks.

Usually it takes 3 weeks for Google, for Bing and others it may take months to start showing images in their results. Basically Zenphoto is not so good when we talk about SEO (search image optimization). Before I start using it I checked that, I tried to find as much as I can sites with Zenphoto and to check how Google index images on them. I checked at least 100 sites and results were very bad, most of them had the same results as you, just few sites had small present of indexed images, and images where indexed badly.

I have several sites whit images and that was very important to me, especially because my expertize is SEO. Finally I had to modify some Zenphoto files to get best SEO and it is working now, I have thousands of visitors from image search every day.

If you wish I will give you my address to check if you do not believe me (you can post yours, I would like to check that problem)?

And please do not believe me, please check any sites with Zenphoto (for example from showcase) and you will see If I am right.

@udaraaka: There are posts about this on the forums already; have you taken a look at those? Such as:

http://www.zenphoto.org/support/topic.php?id=6945

@Jole: Please do post what changes you made for SEO; just saying that you've made changes doesn't benefit anyone. If you're confident in your changes, you could always submit patches to the bugtracker for review. Zenphoto is open source, so contributions are certainly welcome.

Thank a lot for both Jole and kagutsuchi. kagutsuchi, I have checked your link and did the same. I removed disallow part for my cache and albums folder. This question may be stupid but what i don't understand is that why zenphoto developers have disabled indexing those images in cache and albums folders?. One more problem, What would happen if I protect my cache and albums folder by disabling hot-linking using .htaccess file?. Can Google see and index the images in cache and albums folder even when the hotlink protection enabled?

Might just be that those locations are RAW images, not your WEB site pages. Most people want their pages to be the things that are viewed.

Exactly that is the reason why especially the albums folder is disallowed. We might allow the cache folder by default, but it is easily changed and anyone running a site should know a little about these things.

The hotlinking protection is not a server side hotlinking protection. To get that you need to setup a htaccess file for this specifially and allow bots from search engines. We have not done this by default because servers are different and it might cause more trouble. Anyone can do it himself if needed. On our troubleshooting is an entry about that and also a template htaccess file for this.

Thanks a lot for both Sbillard and acrylian.

Just to update: there is indeed a small bug in the sitemap plugin that generates wrong image pages urls (the modrewrite suffix got somehow lost).

This will be fixed in tonight's nightly and this time I see no reason why that updated plugin should not work with the official 1.3.1 release.