I've had a couple people ask me 'what is a developer lounge', other than my explanation here I thought I would post a sample of the kind of discussion that occures throughout the day. As an event at the conference it is nothing else other than a room where developers will come to sit down and do what they do on a day to day basis (email, surf, code, etc); the only difference is that every now and again they break out into spontaneous discussion.
The key really, is having a place where the developer can feel free to talk tech: a space for active discussion (not presentation). The average lounge experiences ebbs and tides of developers coming in and out and discussing everything from their local systems to the latest geek toy.
It is these kinds of open events that allow developers to not only learn what others dveloper are doing, but to also ask questions that they would never ask in front of their peers if it was a presentation that was being given.
On the whole it is a far better method of information dissimination for the engineering community. Furthermore, as more and more of the conference proceedings are recorded, streamed, blogged, posted, etc; it almost makes going to the event redundant because you can wait for people to tell you which presentation were good and then you can go back and watch them after the conference. Meanwhile you can be networking and having syncronous conversation with your peers, whcih is surely what conference were originally about in the first place.