I had this problem recently. And the solution was really simple.<p>My goal was to display in an Rails App the latest entries from a wordpress blog.<p>In the end I used this <a href="http://code.google.com/apis/ajaxfeeds/documentation/" rel="nofollow">http://code.google.com/apis/ajaxfeeds/documentation/</a> which worked perfectly, without any hacks in Rails.<p>You can check it out on www.2performant.com at the bottom. It's all javascript.
I mentioned it in the comments on the article, but I typically just make my Wordpress blog use the same database as my Rails app. Then in the Rails app you can create a BlogPost model or whatever to use anywhere in your rails app.<p>You can either install the WP app on the same server as your Rails app, or you can just create a custom user and SSH tunnel for your DB between the DB server and the WP server.