Blogger has slipped in a (somewhat) quite feature, something that has been long-awaited...custom permalink support. Before you get too happy, let me explain because it might not seem like what it sounds (trust me, I got it wrong the first time too).
At first I thought it was something resembling trackback URLs in WordPress. Its not the case.
You know the Blogger URL architecture, right? An example is blogname.blogspot.com/2012/7/auto-generated-title-url.html Now with this new addition, you can replace the auto generated URL part with your own custom title URL.
As an example, if you have auto generate enabled (it is by default), a post titled "Site Update" will have a title URL as /site-update.html. Now, you can enter your own custom text into the custom field to make the posts URL look like this:
Google did a nice writeup of this feature yesterday, so go here to see the source.
If you are looking for some help, you can also take a look at this new help page that was added.