So, some things have changed since 2007 – I now use the very same permalink structure I warn against below. There are a few reasons for this:

1. WordPress now deals with permalink structure changes much better these days and will automatically 301 redirect the old URLs for you (in most cases).
2. Even if WordPress didn’t do it automatically, I’m now comfortable setting up 301 redirect via .htaccess (which is what I do, because I don’t quite trust leaving it to WordPress).
3. Having the category in the permalink does provide SEO benefits – I don’t care so much about getting the keywords in the URL (you can get that through postname), but I do like the benefits for the site structure (pseudo folders creating a silo structure).

There are still some problems with the /%category%/%postname%/ permalink structure: if you have a lot of pages (more than 50ish), this permalink structure can really slow down your site. Having said that, even this problem is likely to disappear, as it looks like they’ll change the way this works in WordPress 3.3.