As notes MacRumors [1], Apple is hiring [2] a Finder engineer for development related to Finder:

The Finder team is seeking an energetic, motivated software engineer to help develop next generation versions of the Finder, the notorious file browser for Mac OS X.
You will be responsible for developing new features of an application that is often perceived by our users as the "face of the system". You will be working on user interfaces spanning various browser views, new advanced search features, navigation and data presentation as well as many other parts of the application.

In this position you will be expected to:
- Participate in all of the various stages of feature development from design brainstorms, through feature development, all the way to fixing that last critical elusive bug under a tight release deadline.
- You will be required to produce clear designs, excellent implementation and tight code.
- Deliver tight, well implemented features, fix bugs and develop Finder into the best file browser on the planet.
- Work on performance and responsiveness of the Finder, making it feel lightweight, fast, snappy and pleasant to use.

This could be a confirmation to a report [3] we posted in October 2005 revealing some information about Leopard's next generation Finder. The job posting mentions "advanced search features" and "speed improvements", reflecting the extensive use of Spotlight and the performance improvements we had mentioned in our report.