Question: when is a permalink not a permalink?
Answer: when it's generated by Blogger.
What am I on about? Well, the relaunched blogger now creates a single page per post, for the purpose of adding comments and giving the post a permanent link. So what's the problem... that's a great idea, right? Well, blogger bases the URL on the contents of your post (specifically, the heading). For example, this very post has the permalink http://cheshrkat.blogspot.com/2004/05/changing-permalinks-for-fun-and-profit.html
Now, here's the problem. If you change the title, eg. if you re-edit the post to correct a typo, the permalink changes. Hence, the permalink isn't permanent at all. So why not use the old format, with your multi-post archive page and a link anchor? Well you can still do that, but you better pray nobody does something crazy like using the URL where they found the single post and all the comments (like i said, crazy...).
Numeric permalinks may not look pretty, but they work. I understand the desire to be groovy and use plain text, but if it changes anytime the user edits the contents of the post; you've got a problem. I guess bloggers will just have to use the old-style link as a permalink; and hope for the best.