Read Practices of an Agile Developer for the answer to why this is important.
I am primarily a systems engineer and not a developer, however, I find the practice of maintaining this log worthwhile. The secondary benefit of helping others is a driver too.
I have worked for a number of consulting firms in Minneapolis, primarily supporting Windows infrastructure but recently found a great job as the Operations Directory for a small startup. My current job has me working with the technology that I love: UNIX, Linux, virtualization, and cloud infrastructure.
I hope this modest personal knowledge base proves useful to more than myself.