Hey Guys... maybe I'm missing something here.
Yes, it sucks that officially LAN will not be supported in SC2. Why does it suck? Because not everyone will necessarily have access to the internet at say a LAN party, and because the LAG experienced on an internet connection being shared amongst many can be really bad due to bottleneck of the upstream bandwidth (which is generally low on most residential based ADSL lines).
BUT
Really, getting an internet connection shouldn't be a problem, even at a LAN party (just have your buddy hosting the party, share his). We're still left with the LAG issue though, but are we really? Using the example of playing a WC3 game on Battle.net. My friends and I used to try this out, and would all connect to our battle.net accounts. I would host a game and they would all join. Now essentially Battle.Net was being used as an intermediatary for stats and initial handshaking etc. The actual TCP/IP packets were not going via the Battle.NET servers but via the person who hosted the game itself. Now TCP/IP is a routable protocol and therefore automatically able to find the shortest route for a packet to take, thus it will simply send all packets via the switch and between the clients and the server (person who hosted). So in a nutshell, for a locally hosted game, that uses Battle.NET for "authentication", the LAG should be virtually < 1 ms.
Assuming that SC2 works in a similar fashion (and I'm sure it will, as this is more a technical protocol issue, rather than a design one), we should be able to have LAN parties (as long as we can connect to the net), and have 0 lag.