Cups is a pretty confuse thing. It provides a "client" and a 
"server". If you only install the client, then you are bound to only one 
server, configured statically, fine for a desktop with no printer 
attached. This is not convenient on a laptop. For roaming, you need the 
"server". I don't know how to qualify this contraption since the cups 
server is also a client and a much better client than their "client". 
Used as a client, the cups "server" allows roaming.

     This Cups "server" is very badly configured by default, in 
particular on Mac and on Debian as well: browsing all available servers 
for printers and exporting these away. This leads to print jobs 
circulating across laptops before reaching the printer. The first thing 
the admin should do is to decide which host is a server and which is a 
client, and not let any host be both.

     The cups stations used as clients should be configured with a list 
of possible servers, like one at work and one at home. Using automatic 
discovery would be fine if one could assume that servers are only 
servers and clients are only clients, but Cups authors apparently 
decided to mess up everything.

     Didier