Who is Hosting This has put together a great little study into the blog hosts of the top 100 bloggers (according to Technorati).
On top of the list is Media Temple, Datagram, BlogSpot and Six Apart.
Yes you heard it, 8 of the top 100 blogs use Blogspot and 4 use Six Apart to host their blogs. It goes to show that while most (including me) would advise you set up your blog on your own hosting and with a platform like WordPress that you can actually grow a successful blog on a hosted platform like Blogspot.
Of course keep in mind that many of the blogs in the top 100 are in networks so they just go with who everyone else is with in their network and some of the services that the bigger blogs use are probably out of the range of what most bloggers can afford.
If you’re looking for a blog host you might also want to check out ProBlogger Readers Blog Hosting Recommendations (in the comments of that post).