[ale] Ultimate Cell Phone remote?

[charriglists at bellsouth.net (Calvin Harrigan)]

Being the Luddite that I am about portable telephone technology I'm 
turning to the ale community for what might seem like easy questions. 
I'm looking for an ultimate remote control for my mythtv/boxee/hulu/xbmc 
HTPC.  After seeing some of the newer phones with slide out 
keyboards/touch screens etc. I thought these phone would be ideal for an 
uber remote.  The question I had was:  Can these phones, IPhones, 
BlackBerries, generally be used without having service.  As in dedicated 
use as a remote control that communicates via wifi/bluetooth?
Any ideas along these lines?  Obviously I would have to develop an app 
for the platform, just feeling the waters for now.

Thanks