I started working on a blog from last month. My blogs URL was quite big (for ex.
http://my-old-long-url-blog.blogspot.com). I used it because I thought having 2-3 keywords in my URL will help me (I am not really sure that it really helps?).
My blog was getting 22-25 visitors everyday. I changed it's URL 4 days ago & added new URL.
http://autohippo.blogspot.com. In blogger, there is a provision to edit & take any URL, anytime we want.
My old URL posts are still indexed (they appear in Google for particular keywords).
My new URL posts are indexed but not ranked (i.e. when I search
site:http://autohippo.blogspot.comthey appear but i haven't received single visit from Google yet.
I added this URL to my webmasters & even submitted sitemap.