In a previous post I mentioned using my cell phone to carry calendar information. I just did this for a conference I was attending. It was, in fact "good enough" for carrying the schedule I intended to follow, and when I did follow it, it worked pretty well other than trying to read a smallish screen. However, when things changed such as a breakout session being cancelled, the UI of the phone wasn't the best for making updates. Possibly a Treo-like device with more of a keyboard-like interface would work better, if anyone reading this has experience in that vein, let me know in the comments.