While it is planned to make it even easier to create a photo album it is already not so difficult to do it:
Create a new page
Attach the photos one by one to the page
Add the following velocity code in your page:
<a href="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat2.jpg" >
<img src="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat2.jpg" width="200" height="150" />
<a href="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat3.jpg" >
<img src="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat3.jpg" width="200" height="150" />
<a href="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat1.jpg" >
<img src="/xwiki/bin/download/Doc/HowToMakeAPhotoAlbumUsingXWiki/chat1.jpg" width="200" height="150" />
Of course you can change the thumbnail size. You can see the result in this page with 3 images of 'Milou' !
Next step will be to only upload a zip file and create a macro that is able to extract them automatically.