"Can I Use A Blog Address.........................?"
Let's say you have a blog url that you think is perfect and you want to use it for your own blog address. You try to register the name with Blogger.com only to find out that it is already being in use. Just for curiosity sake you visit the url and come to find out that the blog hasn't been updated in quite some time - maybe even a few years.
If you think that this would be a perfect opportunity to be able to use that url as your own then please THINK AGAIN!
As far as I know, Blogger.com will not release a blog's url just because it hasn't been used in a while.
Unfortunately one of your only recourses (if you still want to use that particular url) is to get in touch with the owner of the blog address to see if you can get them to give you their url.
It may be highly unlikely but there have been some cases where people have received a LOT of money by selling their urls!
This may not be good news for those who have a perfect url in mind only to find out that its already been taken but there isn't too much that you can do about it. You'll probably have to come up with a creative solution to giving your blog the kind of url that you want.