Scientists fall asleep during lectures too: talks at scientific conferences like these are no different than other talks and lectures -- there were lots of sleeping people, aided by the dimmed lights, the information overload and the fact that most scientists aren't exactly super-charged motivational speakers.
High-density-poster-induced trauma: There were 300+ posters on display. As if that wasn't enough, some people were apparently under the impression that the right thing to do was cram all the content that's normally in a 5-10 page scientific paper onto their poster, resulting in a 2ft x 3ft [or however large these things are] sheet of paper packed with text in 10-point font, lots of diagrams with multi-coloured data and a bunch of equations. My usual interaction with a poster was to read the title, think "oh, that looks interesting", start to read the text, realize that it'd take me 30 minutes to get through it all, look around the poster for big-picture explanatory diagrams/text, not find any and then stare at the poster for another 30 secs before just giving up and moving on. I think it's fair to say that I got pretty much nothing out of that bit of the conference, mostly because I just wasn't willing to put in the necessary effort.
Mixed feelings: Overall, I found the conference both exciting and depressing. It was depressing in the sense that it served to highlight all the interesting stuff that I'm not working on, and probably will never get to work on. By the same token, it was exciting because it reinforced the fact that there's no shortage of interesting biological questions [that computational methods can help to explore]. Granted, a lot of these questions will not be explored in industry [further reinforcing my "you're not going to get to do anything in that area" bit of depression], but there's still such a huge pile of open questions in the areas important to industry that that's a minor concern.
This was my first scientific conference, so I guess it's another discrete step in my current transition between fields, albeit a rather small step.