Hmmm... that link does look good, but the aligning is done by css. I tried it myself but without succes. I wonder if this is because ZenPhoto doesn't print the actual size of the thumb in the img src code. This way (perhaps) the vertical-align:middle; doesn't work?
This code gives you uncropped and equal(...) size thumbs (got it from another post, so not from my intelligence

):
`<?php
$desirableThumbWidth = 150;
$desirableThumbHeight = 150;
if (isLandscape()) {
$myImgSrc = getCustomImageURL(NULL,$desirableThumbWidth,NULL);
}
else {
$myImgSrc = getCustomImageURL(NULL,NULL,$desirableThumbHeight);
}
?>
[img]<?=$myImgSrc?>[/img]`
instead of the usual print command...