This plugin seems really nice, but there were some annoyances with geting it to work with my customized installation of WordPress, where the wp-content directory is situated outside of the WP directory.
1.) flag-config.php - set your path.
2.) flag.php - line 182-ish, define_constant() function. i had to rewrite the defines for FLAG_ABSPATH and FLAG_URLPATH, because the whole str_replace with a bunch of slashes was a fail. too complicated.
3.) flag.php - line 233-ish, load_scripts() function. WordPress was not generating a proper URL for the swfobject and swfaddress scripts.
this fails: plugins_url('/admin/js/swfobject.js', __FILE__)
this works: plugins_url('/flash-album-gallery/admin/js/swfobject.js')
4.) for some reason when i deployed this to my linux box (was running on a windows box just fine), and activated the plugin from within WP, the FlAGallery page in the admin would prompt me to upgrade the database; i would do so, then come back to the same page and still be prompted to upgrade. I checked out my database, and lo & behold - no tables for flagallery, the plugin activation function wasn't doing its part apparently - so whatever, it didn't recognize that it didn't have tables, and then it can't upgrade those non-existent tables... basically, this plugin has not been programmed to handle that situation... so another big fail right there.
Solved that by copying the tables from the working WP install i have running on my windows box. Then FlAGallery still wanted to upgrade, but when i told it yes, it actually did do the upgrade.
I've written a similar plugin in the past, but was hoping that this would be beefier and easier for my clients to use. It's not exactly as clean/easy as I was hoping, but there's a whole lot underneath the hood, so I think we're gonna stick with this one, and even pay for some of the skins.
My only complaint/recommendation would be for the authors to write stronger integration documentation, with a section on non-standard installations (especially GoDaddy shared deluxe hosting, where little things like $_SERVER['DOCUMENT_ROOT'] can't be trusted). Other than that, gotta give props to the plugin authors also - this is no small feat. There's lots of hours in this bad-boy. Thanks guys!