Important. Your Twitter privacy settings are not reflected in 140Plus. If your updates are private in Twitter it does not mean your 140Plus posts are private.
OK, basic terms of privacy for the site. We store rich tweets and images indefinitely (that means forever, or the closest approximation the site makes to it). Rich Tweets can be deleted in the "my account" section of the site (you can get to it from the home page if you're signed in). When a message is deleted, it is really, properly deleted, we will not be able to get it back for you. We will not "back it up" on the chance you change your mind. It may be backed up as part of our standard hosting company's service in case of hard drive failures, but not in any sinister, tracking you way.
We store your Twitter username, your Twitter display name and the link to your Twitter avatar and background. We do not store passwords since we use OAuth to access your Twitter account.
What we do with your information
Nothing. Really. We use it to post to Twitter and that's it. We collect statistics on visitors through Google Analytics and (potentially) serve ads via Google adwords, but we don't do any keyword processing for our own edification. We don't even have a way to search posts and that is unlikely to change unless Twitter pays us a huge pile of cash to use our hashtags too :)
We will hand over information on request to any law enforcement authority, but seriously, what are the chances of us ever needing to do that?
We *definitely* won't sell, pass on, redistribute or otherwise make available information to third parties, unless we get acquired, in which case the acquiring company will obviously get the rich tweets and images when they take over the site. Third party Twitter clients will be able to display the content of your posts as part of their normal operation. Copyright is retained with the original author. If you post any good jokes we might use them in the pub on Friday night.
We make no promise the service will be available at any specific time or for any specific duration. We do not guarantee your rich tweets and images will be available, nor do we guarantee they won't magically disappear. If they're that important, grab a copy of them. We reserve the right to remove any and all parts of the service at any time and without warning.