Co-incidentally, there was an article this week in the free newspaper Metro about blogs, connected to the Best of Brit Blog Awards 2007. So, as a start, I'll quote from its introductory paragraph.
Blogs have changed the way people communicate, the way the media works and the way information spreads around the world. They have also been responsible for a significant increase in the number of kitten pictures in the world. In the world of blogs, you can find just about anything: informed political commentary that outdoes many papers, deeply involving personal stories, hysterically funny humour writing – and pictures of kittens.
Interestingly, I have just noticed that the word blog is not in Word 2003's spelling check dictionary yet, a mere 4 years later, blogging is so notable that there are national awards dedicated to them!
And, mreow, here is the obligatory kitten picture:

