I have to say I disagree with the whole teaser/article body thing. I really don’t like having RSS feeds that don’t contain the full article. It means I can’t read them offline. I often like to catch up on RSS while offline. I also don’t particularly feel the need to have to make yet another click to view the content of an article.
Yes, it’s a little more bandwidth. But really, it’s cheap. Especially with mod_gzip and whatever else optimised foo we can do.
Maybe planet aggregators could get more clever in summarising entries? Or not. How many people actually read a planet from the web site anyway?