Symphony.

RSS feeds is one of the last things left to implement before I take my site online. I want a couple of feeds: One for all blog entries, one for each blog category, one for comments to each blog post. What's the best way to set this up? I'm thinking having one DS for blog entries, which I also can filter for categories, and one for comments. Would that be the best way to go?

I'd suggest using the same data sources that you used to create your blog. By keeping the URL structure the same, you might be able to achieve this. Perhaps you can map your existing blog URLs into feed URLs as well.

Blog entries

HTML: http://domain.com/blog/
RSS: http://domain.com/rss/blog/

Entries by category

HTML: http://domain.com/blog/category/{category}/
RSS: http://domain.com/rss/blog/category/{category}/

Per-post comments

HTML: http://domain.com/blog/{post-title}/#comments
RSS: http://domain.com/rss/blog/comments/{post-title}

Essentially you're just changing the output method (HTML to XML). So if you have data sources to display the feed data in your HTML pages already, why not re-use them for the XML feeds too.

Ah. Of course. The data is the same, it just another way to display it.