The rise of blogging as a new grassroots publishing medium and the many interesting peculiarities that characterise blogs compared to other genres of documents opened up several new interesting research areas in the information retrieval field. The Blog track was introduced in 2006 as part of the renowned Text REtrieval Conference (TREC) evaluation forum, to drive research on the blogosphere and to facilitate experimentation and evaluation of blog search techniques. This paper reports on two years of the Blog track at TREC. We describe the blog search tasks investigated at TREC, and discuss the main lessons we learnt from the track. We conclude the paper with discussions of the broader implications of the Blog track lessons and possible directions for the future, with the aim to uncover and explore the richness of information available in the blogosphere.