Looks good! I only have one real comment: don't use WordPress's archival system. Listing every month that you've published a post in your sidebar is a terrible way to allow users access to your archives, particularly after you've been online for a year or more.
I still haven't found a really great way to access archives, but the solution I've been using with Wordpress is to create a static page called "archives". The page has no actual content; it's all set via a template page. I usually have lists of both categories and months, and sometimes I'll do a "most popular" style thing, too (for instance, see my
Tagamac archives). Then I place "archives" in the permalink structure (site.com/archives/category/).
I'm not entirely happy with it, but it cuts down the cruft in the sidebar. I'd be interested to see if you come up with a better solution.
I also don't really like the "from the blogosphere" box; it's not centered and the colors/look don't really integrate with the page very well.
Comments look pretty good, although you might want to consider alternating colors (the green with a slightly different green) to make them easier to differentiate.
Overall very nice. I like the flat, non-bubbly non-shadowy look and the hover effects on the sidebar ooze style.