I've got the Calibre server setup on 8787.
http://192.168.1.109:8787/stanza
I can get to it (open it) from any computer on my home network (wired or wireless).
I've got my iPhone4 setup on my wireless network.
When I open MegaReader and go to Download books MegaReader finds the WiFi Book Calibre library. It is using the computer name rather than the IP address.
If I click on that it never connects. If I add it manually using the IP address above it never connects.
So MegaReader can find it. Other computers can open it. It is just that MegaReader cannot open it.