Second Life blogs

Blogs about Main Grid

Oddbits: A Sun employee's blog has sections on her experiences in SL:
http://blogs.sun.com/helzerman/category/Second+Life

New World Notes - journalistic blog about what's going on in SL
http://nwn.blogs.com/

InfoIsland.org: Second Life Library 2.0 - blog about Second Life happenings
http://www.infoisland.org/

This one lists a huge amount of blogs about Second Life, plus lots of other useful URLs
http://opencontent.org/wiki/index.php?title=SecondLife

SciLands - as set of sims focussed specifically on scientific stuff
http://scilands.wordpress.com/

Virtual Grammar - an island owned by Dunoon Grammar School in Scotland - set up on the 20th May 2007.
http://dgs-secondlife.blogspot.com/