Are you accessing the compact flash card in between turning on the wireless and attempting to connect? That may cause the wireless connection to drop out (a bug in the Iliad apparently). If you aren't it sounds like your router configuration may be bad. Those are my only 2 suggestions sorry. I reckon the only things the ping could be doing are
1) waking up the Iliad's wireless, or
2) fixing a problem with the routing.
Try playing around with "arp" on the MAC to see if the iLiad is in the ARP table before and after you ping and play around with the router as well to make sure the two machines can see each other ok. See http://en.wikipedia.org/wiki/Address...ution_Protocol
I'm not sure what the proper mount command syntax would be since I connect from a Windows box.