Update Oct. 22 2009: As of now, due to changes to the verification system in Webmaster Tools, the method explained below no longer works. You can read the announcement in Google Webmaster Central Blog.
So now, to verify a Blogger blog, we have to use the conventional verification meta tag method, just like everyone else :(.
To enable you to access all the features Google Webmaster Tools has to offer, such as crawl errors and query statistics, you must verify ownership of your blog. Google wants to make sure it releases the information to the blog’s rightful owner.
But remember verification itself will not improve your PR or search performance. It only provides you with your blog info and stats, (so you can take action accordingly to improve your blog). Google Webmasters Help says,
Verification doesn't affect PageRank or affect your site's performance in Google's search results.
Anyway, verifying Blogger blogs is very easy, you can do it with just two clicks. Just watch this video, don’t blink because it’s very short. This method is now obsolete, and the video is no longer available.