This is a good idea generally. Of course, some sessions don’t start as technical, but quickly become so (or vice versa!) depending on what participants actually show up (or don’t). Another way would be to color-code the cards/title pages that go up on the wall.
Open Source Bridge has a nice series of “tracks” that might work for this: Business, Chemistry, Cooking, Culture, Hacks. http://opensourcebridge.org/events/2014/schedule
Alternatively, each table/space could be “reserved” for the different categories, but this can be hard to get right to match the demand.
Discourse would be great for this, and you can “Watch” a topic/thread to get e-mail notifications if you want. With all the session threads could go in the “CLS 2014” category (or even subcategories that match the above-mentioned categories) it’d be easy to find info from the event.
One other thing I thought might be nice is having a lunch group “sign up” sheet on the wall. Often lunch time comes and no one has an idea where they can/should go in the (very limited) time available. If some places were recommended then we could have groups established to go there together … might save some wandering and foster more networking.