Value of Blogging - Return on blogging

It's challenging to mark the exact return on a blog. IBM thinks of it this way:

1. Blog ROI comes from the individual relationships and affinities built through communities and conversations
2. Value is added via the knowledge retained, lessons learned, and viewpoints infleunce from blogging

I think of it this way. If your investment to blog is zero, as this blog was, isn't your return then infinite?