Feeds & Aggregators - Really cool. Where is the line?

Feeds are popping up everywhere. Readers and News aggregators are also becoming very popular. If you have no idea what I'm talking about, I suggest you read a few guides or articles. You can start here:

http://www.rssfeedguide.com/

http://en.wikipedia.org/wiki/News_aggregator

A few days ago, I run into a planet. Planet is a very simple yet very powerful Python tool that can download several different feeds, aggregate them into a single one, and post the result on the web. Feedjack also does the job. As an example, you can see some planets here:

Planet Open Office

Planet Apache

Planet Ubuntu

There is, also (and all these are just some examples), an RSS aggregator plug-in available for the Serendipity blog system (which powers this very same website). You can find it in spartacus. By installing this plug-in in your serendipity blog, you can start aggregating feeds from around the web into your blog. This is really cool, and I think I will start doing so. However, I might slightly modify the plug-in or the Smarty templates to clearly differentiate where the posts are coming from (such as changing the colors, or adding a '[from ...'s blog]' notice. or a special category, you-get-the-point) and also to give more credits to their authors, etc.

So now a few questions arise...

Who is the copyright holder for the contents in the feed? Are the feed contents originals, or are they aggregated from other feeds? Are they violating other copyright holders' rights? What are the licenses behind them? Can you freely re-publish them for free in any media? Can you charge for the service of aggregating, or distributing them, or making them searchable, or simply archiving them? Can you make a derivative work and then distribute it for free or for a fee?

Another one: imagine, for example, a politician's or a celebrity feed being re-distributed on another website where the different context makes the content of a few articles from those feeds now to read completely different or inadequate...

How can we know the license feeds and their contents are published under and who is the copyright holder? I am no lawyer, but I guess the easier way is to just browse the publishing blog or website and/or e-mail the author asking if it's OK to do whatever it is you want to do with the content. I bet most of them will be very happy to know you are thinking on re-distributing their content and helping them reach more readers (as long as you clearly identify them as the author).

I know, I know... the original idea behind feeds itself is to easily share and distribute the content, but may be not all feed authors are thinking of their feeds being aggregated or re-distributed. On the other hand, some are only feeding part of their articles. I think at least some of them are just thinking of reaching their readers directly, and have not really considered the possibility of other intermediate sites or other media re-publishing their content, generating derivative works, etc.

So, anyway, there are a few Entrepreneurship, Marketing and Technology feeds out there that I would like to add to this blog, as a free and nice service to my readers. Yes, that's you! . I think I will search and ask their authors for their permission before publishing them though!

Again, I'm not a lawyer and whether something is legal or not is exactly my point. My point here is more about taste, about etiquette. It's just that ... it seems a bit rude to me to re-publish others' content without at least asking and letting them know what you are planning to do with it (unless of course they have clearly identified you have the freedom to do that --check out my content license on the right side bar!). Adding a link to their blog or site also seems like the good thing to do (and most planets do).

There are also some sites that the only thing they provide is the aggregation of other sites' feeds. If they don't provide any original content nor they provide any service other than aggregating other sites' content, How do you feel about them? How do you feel about them making money from the advertisements? What about if they are trying to make you believe it is their original content? Where is the line?

How do you feel about them if, when you search google for the keywords they represent (let's say, for instance, the name of a given celebrity), all you can find is these kind of sites? Should google penalize them on their page rank?