Ideally one should be able to create feeds to any type of content. The planet feed would look like so:

http://www.biostars.org/feeds/type/blog/

that being said, now that I looked at it this particular feed does not seem to work properly.

I never tested it as it everything feed routes through the same code so it is surprising. I do have a sense of what the problem is likely caused by - for planet feeds the posts do not have the same type of body content as the regular posts. I'll add a fix in a few days and post it back here.

Also opened a GitHub issue for it

https://github.com/ialbert/biostar-central/issues/197