Hmmm... so blogger.com now supports labels for posts. Since its a Google product, I am guessing that labels will influence search engine relevancy, especially if the label appears in the title or post text. Same would apply to tags at other sites.
Meta-tags haven't been relevant in SEO for a couple of years now, but perhaps Google is thinking about (or has done it) giving weight to content tags? This is pure speculation, I haven't the foggiest idea. Although I have noticed that I have gotten a lot of traffic to my personal blog when search engine queries match my labels. Interesting.