I have 2 iPod Touches, one is a 3rd generation on which I have always been able to connect with Calibre and the other is a brand new 4th generation which wouldn't - up until today... I don't know why, but but today I tried again and it works!
However, the point of my post is that you can set up Calibre in the Stanza "book sources" using your local ip address in the URL field, in this format:
http://192.168.1.50:8080/stanza where 8080 is the default port in Calibre--preferences--sharing over the net. On a PC, to find your IP address, click on Start and type "cmd" into the search box. On the DOS window that opens, type "ipconfig" and write down your IPv4 Address to use in Stanza in the book sources.
It works even if you can't connect directly using the usual "computers sharing books" (because Stanza is always "searching").