In the light of Microsoft changing there licensing rules for RSS search results I thought it would be a good opportunity to revisit the age old issue of RSS fair usage.
Current state of affairs
If you take a brief look around the internet it won't be long before you find a site that is displaying the contents of another sites RSS feed. A common reason for this is where webmasters republish RSS on their sites to give Google the impression to site is constantly being updated.
Webmasters will often use popular mainstream newsfeeds from sites such as Yahoo then parse them into their own website using tools such as Magpie so that the Google bots have something to crawl.
Dig still deeper and you may find sites that scrape RSS feeds and republish them verbatim. Again this is for the usually financial gain of the webmaster. The webmaster of the scraper site has source of fresh content that auto updates, is readable by Google and is usually monetized using Adsense.
The dark side of RSS
This sort of use of RSS for republishing for financial gain would be considered to be on the more dubious side for RSS usage. RSS is all about syndication for both personal consumption and to a lesser extent commercial republishing, so where is the line to be drawn.
Fair usage of RSS
Consuming an RSS feed in your RSS reader I think we can all agree on is fine, that is why publishers publish RSS. What is less clear is whether or not someone can take an RSS feed and publish it on their own site.
Why would someone want to republish an RSS feed on their website? The reason is usually financial. Is it right? Everyone is going to have their own answer to that question. In my opinion as long as clear spiderable links are used giving clear attribution then it seems fine. I am sure most webmasters would appreciate the extra traffic although I would also recommend that you contact the feeds publisher as a courtesy to let them know what you are doing. At least then they can ask you to stop if they feel it is infringing on there copyright.