Both, Apple's OS X 10.3.4 update and FreeBSD's release of version 4.10 put a new kernel onto a substantial number of machines I run and administer. (Actually, only the FreeBSD 5.2.1 and Gentoo machines are exempt).

While the 4.9er machines are all servers and have been chugging along dutifully and satisfactorily ever since (so no big change there), I'm happy to report, that the new kernel (along with other enhancements such as networking code and graphics drivers) have made my desktop experience snappier[tm] ;-) Even third-party-apps such as NetNewsWire are now noticably more responsive. Thanks!