I've used Posterous for a while it has it's good and bad aspects.It's major downfall is that it's difficult to edit,
it's hard to explain exactly how it works but it a majot PITA.For much easier interface try
www.xanga.com.
If you sign up with
johnsmith@gmail.com your posterous blog will be
www.johnsmith.posterous.com.
You should be careful which email provider you use to sign up. Yahoo for example has an ad for it's toolbar on every email and as I mentioned it's difficult to edit out,
www.gmx.com is great no taglines or ads at all.
You can post to your blog from multiple accounts.