I use a block with my feeds and I added a link to feeds.html in my navigation.
Does it make sence to use rel= nofollow for all links within the feed block or should I better use only my navigation for feeds ?
Any tips information about duplicate content and feeds ?

As we know, not all search engines adhere to the no-follow and no-index and even ones that do, can index a link even if it is a no-follow.
Personally, I'm slowly reviewing all links on my site and where I have duplicate content, I'm trying to identify which of those links I should keep 'public' for better for SEO and which links I should 'hide' by wrapping them in a user test.
I have no problem giving my users different ways to find the same content - News, Articles & Authors, Topics etc

Back to the feeds its known if you use Wordpress there is problem with duplicate content and feeds of course with other links in wordpress too.
I think I will use just my navigation with a link to feeds and maybe I use rel nofollow.

Hello! If you break up your posts, show only a sample intro, or your first paragraph in the $hometext (which is shown in your feeds) and post the majority of your article in your $bodytext, then everywhere your feed is syndicated will only have the first chunk of your article, with your title as a link back to the original, full article. According to what I read on google blog, if your website is identified as the original source, through a link back to it, it shouldnt be a problem. If you use nofollow on your feed links back to your site, this may effect that.



http://googlewebmastercentral.blogspot.com/2008/06/duplicate-content-due-to-scrapers.html