This looks promising… for those who like tag clouds: A Plugin for WordPress 2.3: Include Categories in the Tag Cloud. I, however, am not one of those people. Ahem.
If you’re into creating themes, or want to start, this Check List for WordPress Designers may be of help.
And, lastly, here’s another post on search engine optimization in WordPress: Simple WordPress SEO Tips
All in all, not a busy week on this front.