I often see search results from 192.168.x.y, or 10.x.y.z, which I'll never be able to contact. I tried putting 192.168.0.,0/16 in the hosts filter (I'm using 1.7c), but to no avail.
Also, it would be great if you could give limewire a local script that returns the ip address, and give the option to 'at' the job periodically, so shared connection DSL users can keep a good current ip in the field.