The new Photo Gallery (which has been in testing on the beta site for some time) is now available for everyone to use. Here you can see examples of the photo gallery in action:
To use it
That's it! Now your friends can view your photos by going to photos.yourusername.fastmail.fm.
You can specify comments for your photos by going to the folder with your photos in file storage, selecting the Action: "View as photos", and then clicking "Do". Now you should be able to enter a comment for each picture.
I'll be adding a detailed FAQ section in the next day or so.