They say that the best way to learn something is to teach it. In the context of learning and training, I see blogging as a way to process information, reflect on a topic, express opinions and thoughts and connect with and learn from like-minded others.
As for the potential advantages of blogging, I agree with the eLearning Provocateur that blogging is “a forum for free thought – something very rare in this fast paced, time poor, ultra standardised world”.
If you need more convincing about the advantages of blogging for learning, visit the Knowledge Start Blog list of 121 Blogs About Learning.
Potential disadvantages I see are that maintaining a blog can be a lot of work and if you want to keep readers interested you would need to post regularly which could take discipline.