uninstalld appears to belong to a new "Uninstall" framework that comes with OS X Lion.
It sits in:
What does it do? I don't know specifically, but here's what AppleInsider says (based on a blog entry here):
Additionally, the discovery of a new Uninstall.framework indicates
that new Profile Server remote management tools (a feature of Lion
Server for both Mac and iOS clients) will enable network
administrators to remotely manage the software installed and removed
on an organizations' machines, in addition to managing profiles
(configuration files that are currently used to set up new iOS
devices, and will in the future be used to set up Lion Macs).