Thoughts on large disk reliability and raid maintenance?

[buhrow%lothlorien.nfbcal.org@localhost (Brian Buhrow)]

        Hello.  I've just been reading this blog on the reliability of larger
and larger disks:

http://alumnit.ca/~apenwarr/log/?m=200809#08

        I wonder if it might be useful to add a thread which slowly and
continuously reads the raid set over and over again, testing for bad
sectors and, as he suggests, writing them back to the affected drives.
I've certainly run into situations where a sector went bad on a raid set,
then, when I went to rebuild the raid set, found that other sectors on
other drives were bad.
thoughts?
-Brian