Requirements from http://wiki.netbsd.org/projects/project/bulktracker/

[bsiegert]

• track commits (additions, updates), show reports about which packages have not been bulk-built after the update on which platform
• summary of broken packages, per platform (similar to Cross-correlate single package #3)

[bsiegert]

The easiest way to get a list of updated packages (I guess), would be to regularly read and parse http://ftp.netbsd.org/pub/pkgsrc/current/pkgsrc/INDEX.