SeaView is written using open source, including Tapestry, HiveMind and Hibernate. This is the first commercial product (as opposed to hosted application) that uses Tapestry in this way. I'd bet there are others out there I don't know about.
Update: ... certainly not the first. I'm getting senile. I did a two-day training session at Widen last year. They sell a shrink-wrap digital asset management product, written in Tapestry.