Infoworld's lead article, The battle for the blogosphere, contains some interesting info on MSN Spaces. It says:
Introduced in beta form just last December, MSN Spaces now hosts over 10 million blogs, an eye-popping adoption rate that has blown past internal Microsoft expectations. "MSN Spaces is the fastest growing service MSN has ever introduced," said Brooke Richardson, lead product manager at MSN communication services.
Compare this with a comment from the founder of Technorati, dated May 16, which says: "This weekend Technorati tracked its 10 Millionth Blog".
Now, nobody really knows how many blogs there are, even counting the 12 million Korean ones, nobody knows how many are simply spam, and no-one knows how many will be abandoned in anything from 2 hours to 2 weeks.
However, I think MSN Spaces must be well on the way to fulfilling my opening prediction, in Microsoft launch[es] blogging software (December 9, 2004), that "Microsoft could soon be the biggest company in the blogosphere."