Pois é, cá estou de novo...
Minha impressora estava funcionando normalmente quando, do nada, parou...
Fui na "ajuda" do CUPS e lá apareceram as seguintes mensagens de erro:
D [31/Aug/2010:23:18:51 -0300] cupsdSetBusyState: Printing jobs and dirty files
D [31/Aug/2010:23:18:51 -0300] cupsdAcceptClient: 18 from localhost (Domain)
D [31/Aug/2010:23:18:51 -0300] cupsdReadClient: 18 GET /admin/log/error_log HTTP/1.1
D [31/Aug/2010:23:18:51 -0300] cupsdSetBusyState: Active clients, printing jobs, and dirty files
D [31/Aug/2010:23:18:51 -0300] cupsdAuthorize: No authentication data provided.