Bora Zivkovic of A blog Around the Clock has written a short history of science blogging [Science Blogs – definition, and a history]. It's well worth reading since Bora has been active for a long time and he's very well connected to the science blogging community.
Here's how he describes the category that applies to Sandwalk.
The earliest science bloggers were those who started out doing something else online – updating their websites frequently, or participating in Usenet groups – then moving their stuff to blogging software once it became available in the late 1990s and early 2000s.In my case the usenet groups were talk.origins and sci.bio.evolution. Both of those groups are hosted on a server in my office; talk.origins is still very active but sci.bio.evolution isn't.
As much of the early online activity focused on countering anti-science claims, e.g., the groups battling against Creationism on Usenet, it is not surprising that many of the early science bloggers came out of this fora and were hardly distinguishable in form, topics and style from political bloggers. They brought a degree of Usenet style into their blogs as well: combative and critical of various anti-science forces in the society.
PZ Myers is the most famous talk.origins veteran. He's the one who convinced me to start a blog back in 2006 when I realized that blogs had many advantages over usenet, especially images. I don't know how many other talk.origins veterans have a blog. Can you help me out? Here's a partial list. (Some of these blogs are not science blogs.)
PZ Myers: Pharyngula
John Wilkins: Evolving Thoughts
Jeffrey Shallit: Recursivity
Jim Lippard: The Lippard Blog
various people: Panda's Thumb
John (catshark) Pieret: Thoughts in a Haystack
Troy Britain: Playing Chess with Pigeons
I know there are many more but I just can't remember them right now.
The other thing that Bora points out is that many science bloggers were connected to each other in different ways. Often we had met in person—this is certainly true of the talk.origins veterans. The early blogs were characterized by in jokes and incestuous cross links.
This has now disappeared as a whole new generation of science bloggers have entered the blogosphere, although there's still a certain amount of personal contact (see Evolution and Poutine and Beaver Tails.) I don't know if this is important or not. Blogger cliques can be a good thing and a bad thing.