I hope this doesn't track what I'm reading unlike the new readability.
URLs are tracked, though -- they would be tracked in my server logs, even if I didn't do anything specific to track them.
But they are intentionally tracked -- and a percentage of them are run through an automated Readable test, every day, so that I can see, on average, how often Readable gets things wrong.
However, you'll just have to take my word for it that I won't be reading the server logs -- which contain the same, if not more, data.
http://readable.tastefulwords.com/faq/
Still, not 100% sure if the URL is considered text too and is not sent anywhere.