Seen at Anime Diet with a reference to ANN:

The Society for the Promotion of Japanese Animation, the parent company of Anime Expo (AX), has announced that it has hired a third-party company to oversee registration starting in 2008. Experient's services will include a dedicated pre-registration site with group and hotel reservation options, a scannable confirmation form for quicker on-site processing of pre-registered attendees, 60 manned and 40 self-registration stations, and on-site and on-call support from Experient's personnel.

I always worked around this by registering on Friday. At worst it took 40 minutes. However, in 2004 my car sustained a lower ball joint separation while I was about to depart for AX. Getting it towed took a while and I checked in the hotel around 23:00, when registration was closed. The next day I stood in line for six hours. No, I'm not exaggerating. I went to register at 8 in the morning and received my badge by 2 in the afternoon. Needless to say, I missed the opening ceremonies, which I really wanted to see.

Moreover, I think that organizers screwed me ower. Instead of creating a single line, they separated the crowd into individual segments. I'm quite certain that other segments overtook the one where I ended.