How to examine FreeBSD source changes with CVS?

[Pete Slagle]

I seek education about FreeBSD source control spelunking.

I noticed that GENERIC was updated recently in 6-STABLE, and I would 
like to see what changed. More generally, how does one examine diffs in 
the FreeBSD source as it changes?

Could some kind soul demonstrate how to do that with CVS? Or point me to 
the right FM (as in RTFM). Or suggest a better method.