eggcups uses com.redhat.Hal.Device.Printer to try to configure a printer, but the correct interface name is org.freedesktop.Hal.Device.Printer. This is another part of bug #214599.
Fixed in devel:0.19-18, FC-6:0.19-17.0.1
Oops, still broken. Really fixed in 0.19-20.fc6.