Is there software available that will enable an iPod both to store and
broadcast DVD movies in the appropriate format?  I think it'd be cool
if we could store movies on an iPod and broadcast them via the
appropriate output jack to a TV.

Technically, this isn't possible with an iPod. By the sounds of it,
you wish to play DVDs directly off the iPod without use of a computer.
The new iPod Photo technically has the possibility of doing this but
doesn't have the processing power nor is there software available to
do this. If you were to use a computer, this would only be copying the
data from a non-encrypted DVD to the iPod. (If the DVD is encrypted
like all DVD's purchased in stores, a decrypter would have to be
used.)

by the time you upgraded your ipod to the specifications for playing a
dvd, it would weigh as much as the computer you got it off of