Beware of one difference between the GNU gettext API and the PHP binding of it, which is that the GNU gettext functions that accept a $count parameter all expect (indeed, being compiled C, require) that $count be unsigned, while the PHP binding does not.
Thus, the PHP gettext functions will happily accept negative numbers. The one potentially irritating consequence of this is that -1 is treated as plural, which sits well with some people and not so well with others. (As a picky native speaker of English, my personal opinion is that both "the temperature is minus one degree Fahrenheit" and "four apples minus five apples leaves minus one apple" but others may feel that "four apples minus five apples leaves minus one apples" sounds better.)
The upshot: You may want to abs($count) before passing numbers to gettext.
Bonus points: If your application includes user preferences, you might offer a "treat -1 as singular" option to your users, then choose $count or abs($count) to pass to gettext based on each user's preference.
