Great question, actually, because as you suspect, being able to 'cross-pollinate' your sites is a smart strategy, where each time you post on any of your sites, you get the benefit of new material on all of them.

However...

The flip side of this, the dark side, is duplicate content, with a healthy measure of "IP theft" thrown in for bad luck.

What I mean by this is that you can't have the same material show up on multiple sites in total without causing trouble for yourself in the long run with Google and other search engines. Why? Because the search engines need to minimize the risk of having scrapers duplicate sites wholesale to gain search engine result ranking. For example, if you put the effort into writing a dozen scholarly articles on a particular subject, you wouldn't want others copying that article and ranking ahead of you in search results, would you?

There's an ethical side to this too, where it's just not cool - or ethical or, in most cases, even legal - to copy material from another Web site without explicit permission. Just because the NY Times has articles online doesn't mean that you can or should use a quick "copy and paste" to get more content for your site.

Both of these apply to syndication in a big, big way because even if you're okay with others having a copy of your content, you might want to carefully think about the risk of overt content duplication and the fact that you are now competing against your own content on other sites for higher search engine ranking.

This is one of the conundrums with article repositories like eZine Articles: if you give them the same article you already have on your site, you're opening up all sorts of problems. That's why smart people who use article syndication submit articles that they've never published on their own site, either through [often dopey] article spinning software tweaks or simply by writing unique content for the repository.

This could be applied for your blog by having a summary of your article that only shows up in your RSS feed, for example, a 2-3 sentence overview that you write fresh and don't copy and paste from the article or entry itself. Then even if dozens of sites automatically syndicate your RSS feed as content for their own site, you get the backlinks (good) without the duplication of content with what's on your own site (bad).

That's why I have the cross-pollination on my site, but it's only the titles of the articles, not even a single line of the content itself. Nothing for me to worry about with the search engines, but the links themselves show up in multiple places to help get the indexing process started.

Behind the scenes, I do it by having my blogging software, Movable Type, produce tiny text files that just contain a single entry title or similar. For example, here's a snippet of the code on the intuitive.com home page that pulls in the titles of the two latest blog entries:

That file contains just this:

This won't work when you have multiple sites on multiple servers or when you're using a third-party service like MySpace, Facebook or Digg, but since all of my sites are on one server (with one shared IP, SEO geeks out there I'm talkin' to you) it makes this sort of thing rather straightforward to accomplish.

I realize this is a bit of a rambling answer, but I hope it helps you figure out whether you want to syndicate your blog content and what kind of results you might see.