I'm using "a poor man's SUS" almost every day. Here's how:

I'm doing consulting and service at clients sites. And when I have to update the client's machines, I just plug my PowerBook into their network and start my customised Squid (proxy).
I am using Squidman (Mac OS X GUI for squid), made some changes to the default cachesize, increased the maximum file size to 300MB and the cachedir to 3GB. That's all.

On the client machines I just change the ProxySettings to MyPowerBook.local:8080 and off we go!

On a fast LAN it's a pleasure to see how fast it goes.

And I can even profit from my own Squid if I have to update my own PowerBook. I just change my own Proxy Setting to localhost:8080 and whoooosh! :)

OK - it needs a manual change in every client machine, but it's still faster than updating without a SUS.

By the way: No problem to fast-update Windows machines the same way... It just works! :)

this is smart - i've been thinking about the same, having all updates with me when going onsite! although i was planning to setup my apache to do it - swupd is just another apache server.