Since i’ve just started blogging, what I did was edit my admin entries one by one; I copied the entry, memorized the title and excerpt, logged out admin, logged in my username, wrote a blog and pasted into the entry area the text I had copied…
But I wish WordPress developers heed the wish of posters here: An admin feature to change ownership of certain blogs. I have not even found this on (the latest) version 1.2.