first of all thanks for such a great comprehensive plugin!
I have run into an issue using Link Library together with Otto's Simple Facebook Connect http://wordpress.org/extend/plugins/simple-facebook-connect/
As far as I can see SFC parses the_content() to add facebook metadata to the header of a post, which means the shortcodes get executed more than once on a page.
I thought I managed to fix the issue by enclosing the offending shortcode function (link_library_addlink_func()) with an output buffer, as it currently echos validation messages, rather than return them.
While this sorts out the multiple validation messages I still can't get it to play nicely with SFC, since the postdata gets processed 3 times.
I'm not sure what the best course of action to fix this is (maybe post to a separate file rather the same form?). Do you have any ideas ?
I guess the other option is to disable SFC on Link Library pages, as outlined here: http://wordpress.org/support/topic/plugin-simple-facebook-connect-questions-suggestions-re-newdev-version