Edit: Don't take this post for gospel, it might not be accurate.
I'm not about to go and argue with a super moderator
, but I think that all of the solutions mentioned above are for tethering the device
to a pc; I don't think you can create a wi-fi link
between two phones any more than you can two laptops.
The reason is that Ethernet (in the case of a wi-fi connection, but also some USB and Bluetooth devices) is basically using a star configuration where nodes need to connect to a hub -- you can only connect two nodes together if one of them can be made to act as a hub. Now, some devices are able to run in both hub and node modes (the OpenMoko comes to mind). I don't think Android and/or the current hardware supports this. Yet, anyway.
What I'm saying is that you need features in hardware, or at the very least in software, that just aren't available.
Disregarding all I've just said, it would be
awesome to have any Android phone act as a wi-fi walkie-talkie!