I am using the latest release 2.1 and I can't get the images in the albums to sort by their file name in descending order. I have both the sub-album and image sort by file name with the descending check box checked, yet the images do not get reordered. For good measure I also tried to set the gallery default to sort by image name, descending, yet the images stay in the original sort order which was date, ascending.

Is there anything I can do to resort the images by their file name but in descending order?

I assume you mean release 1.2.1. Anyway, you should give the nightly build a try and see it the problem exists there.

I just discovered that by selecting sort by id, the images in the album are apparently sorted randomly, which is very nice. I don't know if this is by design or accidental. I thought
that the id's are sequential so sorting descending by id would be the same as sorting descending by file name. Anyway, it is a nice feature if the id's are indeed random.

Not so much randomly, but by the order zenphoto discovered them. The ID spans the entire gallery, so for any single album it will be sequential with gaps.

Not sure they are quite sequential, it's as if the files were not read sequentially from the folder I put them in. I have over 250 images in this particular album, all numbered sequentially, with gaps for deleted files. So, if the ids are sequential, as I thought, then the id sort order would match the file name sort order, unless the files were not read from disk in their natural sort order and the ids therefore do not quite follow their sequence.

Anyway, I actually like this "feature" of pseudo-randomness, wanted or not, because the images in the album look better if they are taken out of their shooting sequence and then re-mixed, at least for this album which is a very long sequence of portrait shots.

No, the id order does not match the filename order. You need to know how Zenphoto works to understand that. Zenphoto uses the lazy evaluation way and is filesystem based. That means that if you have 250 images uploaded via ftp for example, Zenphoto does not know about these images unless you or someone else visits the album and the images the first time. Then they will be added to the database (and the thumbnails etc. are generated and cached). That means if you for example view image #100 as the first it will have the lowest id. That is what sbillard meant with the "order of discovery". So these two order settings do not match necessarily.
In case you are interessted here is a simplified diagram about how Zenphoto works: http://www.zenphoto.org/wp-content/uploads/2008/09/zenphoto-12-image-discovery12.pdf

Ok, got it, that explains it; thanks for the info, it is very kind of you.

It seems that I have the same problem. I have an album, with two subalbums. When I want images in the albums to apper in a way that the oldest one are on the top, and the newst ones are on the bottom—I fail.

In administration I set up: Options > gallery configuration > Sort gallery by: Date (descending is UNticked).
But when I go to Edit > click on the gallery name to edit the presets > Sort images by: Date (descending is UNticked). HERE is a problem, when I try to save this UNTICKED preset, it automatically jumps back, after I click on the "save album" button.

I use version 1.2.2 [2983]

Do you know where the problem could be?

I beleive that there has been a fix to this problem in the current nightly builds.