Uncompressed digital 1080p requires 50 Mbit/frame approximately. So assuming you're talking about running 25 frames per second then you need a continuous bandwidth of 1.25Gbit/s (this will scale linearly with frame rate - so 50 frames per second is 2.5Gbit/s, etc.). That's not available even to wired users (wireless tops out at 108Mbit/s, mostly, wired is 1Gbit/s unless you have newer 10Gbit/s interfaces which are mostly restricted to server equipment at present).
DLNA is a closed standard - it costs $5000 to buy the specs, apparently, so even though they're no doubt leveraging the mountain of free s/w out there, the DLNA members have chosen to keep their standards proprietary. For that reason alone you should not use it. See:
http://gxben.wordpress.com/2008/08/24/w ... l-so-much/ for an overview of the protocol (it's crap, of course).
Anyway, back to the topic - you _can_ stream 1080p over wireless to DLNA device because DLNA doesn't stream raw video (as indeed it could not - see above maffs), rather it streams MPEG (or WMV) in a rather limited set of profiles; these will correspond to the broadcast profiles for HD; for MPEG-2 that's 10-20Mbit/s and for MPEG-4 that's <10Mbit/s. So either of these will go over 802.11g provided the network is running at full bandwidth with no interference.
The mandatory MPEG component in any HD media distribution rather makes a mockery of the HD standard in the first place (yes, there are more pixels, yes they flick on and off more quickly, but the only way we can drive all those pixels is to send the media compressed with blurr-o-vision MPEG-2 (ever wondered where those strange blocks come from on digital broadcast displays? They're caused by MPEG running out of capacity to encode the information in the display, so it gives up)).
Still, with the hype out there you would think it was no longer possible to watch television without HD ...
Cheers,
Robin