According to the Substance Labs blog post, the site idea came from noticing the social dynamics that happen at SXSW each year. In their words:

So we thought (as we often do), wouldn't it be cool to combine the random meeting of people with the lessons learned from SXSW presentations? After some quick emails back to SWHQ to discuss, the idea for SXSWLesson.com was born.

We think that SL is on to something here - the reason so many people go to SXSW Interactive in the first place is to bump into other people, have inspiring discussions about stuff, make new friends and overall learn a lot. The panels only go so far, and this tool elegantly captures the gestalt of the conference, random topics, spontaneous conversations, and new stuff to learn.

This is one of the very few really good uses for Twitter hashtags that we have seen. Take a suggestion from us and bookmark SXSW Lesson; we think it has a lot of potential. Just wait, you will see increasing activity and new submissions coming in all the time. Plus, it acts as yet another way to generate a list of really awesome people to follow on Twitter, and that's a definite value-add in our book.