<p>Do you think that writing about software (i.e. having a blog) and speaking on software (and concepts) make you a better programmer?</p>

Statistically speaking yes. You only retain about 20% of what you read and hear, but 80% of what you teach.
By writing about something or teaching about it, you force yourself to understand the concepts on a much deeper level.
UPDATE:
I wanted to update this with some links to more concrete data to support the statistics that I have been taught numerous times about learning retention rates. However, it would appear there is some
controversy surrounding these numbers
, even though the
NTL Institute for Applied Behavioral Science
maintains that research was done to back them up.