Is there anyway (not too hard :) to have all the thumbs on the "index page" to the album be the same size whether the actual image is portrait or landscape? I'm finding the page looks quite messy having them two different sizes.

Try the crop option in admin options.

Thanks, that works. "Crop" was misleading a word as I didn't know if it was really "proportional scale to size" that's being done so I had the option unchecked.

Actually, I take the above back. The "rescaling" isn't proper. I have thumbs in an offline album that Photoshop created. They're proportionally scaled from the full image. So, in essence, the Zenphoto copies should resemble them. They don't

I'm viewing thumbs where my hea in lopped off! Seriously, how can I publish an album with heads lopped off

The crop option does exactly what is say, it crops the thumbs and does not resize them. Uncheck the crop option and set the crop height and widht to the same size than the thumbnail size. Then yoiu should get uncropped thumbs in there original proportions.

If I uncheck and manually set, will the portrait be say, 90x60 and the landscape 60x90? Are the thumbs produced on-the-fly or is there a directory I can FTP my own thumbs?

Yes, accordingly to there proportions. Why don't you just try it?...:-)

And yes, the thumbs are produced on the fly. They are within the cache folder and look like this:
image.jpg_100_cw85_ch85.jpg (meaning thumbnail size 100 with 85 crop height and width). I have never tried to copy thumbs manually, you probably could do that, but you have to name them that way and have to match the settings, otherwise they would get processed. And keep in mind that if you delete the cache for the gallery or an album, they all would be gone.

I just tried. I set ALL images to 130x130 so in fact, whether portrait or landscape, they'd take the same amount of space. I set for 24 images per page. Got mish mash. The landscape are 3 or 4 across. Where there's a portrait in the row, it's not sized to square so takes up more room thus causing misaligned rows.

I just got email from my girlfriend who posted her pics on Facebook. The index is what I want (assuming the sideways portrait ones are not the fault of Facebook). They're all same sized.

acrylian:
Is the URL posted to Features, by you, what I am looking for?

http://www.zenphoto.org/documentation/zenphoto/_template-functions.php.html#functionprintCustomSizedImageMaxHeight

I tried the link but couldn't find reference to resizing.

Well, I took a quick look at the facebook demo tour. What I see there as an example for the photo gallery is exactly what zenphoto does when the thumbs are not set to cropping. It shows landscape and portrait thumbs. Of course the standard themes are build for cropped square thumbnails, so you need to modify your theme's CSS to get that showing correctly.
If you want really 130x130 square thumbs you need to use the crop function.

The function above is originally for the image on image.php and not for thumbs since it uses the size of that images as a value.