I installed it, and Gallery 1.4.4 works GREAT - there were issues with 1.4.3 when trying to add photos, the form based upload didn't always work in Mozilla.
Anyways, 1.4.4 works great, and the included install in the Contrib/Mambo folder (in the gallery package) works fine. Additionally, Mambo 4.5.1 can run gallery.
I have a working Mambo 4.5.1 with Gallery 1.4.4 at
http://avinator.com
If you need more help let me know.
<rant>I've played with several other galleries, and my 2nd favorite is Zoom - which is also very very good, and integrates perfectly with Mambo's ACL. However, I like Gallery (from menalto) because it has more options to add nice frames around pictures. Additionally, Gallery is easier to administer - to move photos around, delete, etc (especially with the Java tools or Gallery remote) However, Zoom is the best Mambo based photo gallery (with support for movies/flash in the future). RSgallery is being dropped, and AkoGallery is hard to work with.
I like Coppermine too, and I would prefer to use it, but Gallery is extremely powerful and does everything well, once you get used to it. Like I said, Zoom gallery is also very good, and much easier to install.
Gallery is a little tricky to install, but point the Mambo component installer to the contrib/mambo/ directory in the Gallery package. </rant>