Second Life blogs
Blogs about Main Grid
Oddbits: A Sun employee's blog has sections on her experiences in SL:
New World Notes - journalistic blog about what's going on in SL
InfoIsland.org: Second Life Library 2.0 - blog about Second Life happenings
New World Notes: reports from SecondLife
This one lists a huge amount of blogs about Second Life, plus lots of other useful URLs
SciLands - as set of sims focussed specifically on scientific stuff
Blogs about the Teen Grid
Virtual Grammar - an island owned by Dunoon Grammar School in Scotland - set up on the 20th May 2007.
Schome Park - the schome community's very own island ...