Here's a bottleneck for you "singularity" guys that ultimately limits the height of parabolic rises: Infrastructure. Remember when MtGox had an order queue of up to 75 minutes filled with market sells? Think this can't happen again in some other variation? Think again.
Spot on. However... a solid infrastructure can ( must? ) be built on top a large ecosystem of users. Traders are kind of meta-users, if adoption starts to spread, then trading it's just there in it's corner and it's no biggie if Gox or whatever market is down.
It worries me to a certain degree that there doesn't appear to be a steady growth of services and stores accepting bitcoins.