There are two feature length films I know of made with Poser:

Dominator was shown in theaters and released on DVD:
http://us.imdb.com/title/tt0135991/

Monsters of the Id is an amateur film available from the author:
http://www.monstersmovie.com/

I guess there aren't more because for an amateur a feature length film is a fairly daunting undertaking. That's a seriously large amount of animation for one person to do.

Profesional studios on the other hand need more robust rendering for high resolution output and would have little need for the features of a application like Poser with apps like Maya at their disposal.