SEO Tip #24: Does the position of keywords in the URL affect ranking?
Matt Cutts: Truthfully I wouldn’t really obsess about it at that level of detail. It does help a little bit to have keywords in the URL. It doesn’t help so much that you should go stuffing a ton of keywords into your URL.
You know if there’s a convenient way that’s good for users where you have four or five keywords that might be worthwhile, but I wouldn’t obsess about it to that level of how deep is the URL in the path or how am I combining it?
For example, on my blog, when I do a post I’ll take the first four or five words or two or three words related to that post and I’ll use that as the URL. But you don’t need to make seven, eight, ten, twenty words because that just looks spammy to users and people will probably not click through as much in the first place.
So position is going to be a very, very second order kind of thing of keywords in the URLs. I would not worry about that so much as having great content that people want to link to and people want to find out about.