Use FB like button to lock content?

No, there's no way to do that. Facebook doesn't actually let you see what users have Like'd a page on your site, so there's actually no way to block that content from them. They do this to prevent 'gaming' the system by forcing or otherwise incentivizing Likes.

Hope that helps explain, and glad you're liking JFBConnect. Should you have any other questions, just let us know!

Finally, please consider leaving a rating and review on the Joomla Extension Directory for JFBConnect, or our support. It's certainly not required, but very appreciated!
extensions.joomla.org/extensions/social-...ook-integration/7215

Thanks,
Alex

Excellent questions!

For the Joomla example you give, that works with a Facebook Fan Page. JFBConnect supports this built in (you must Like the FB Page to see the content underneath). You can read more about how to configure the "Reveal Page" feature on the page below:
www.sourcecoast.com/jfbconnect/docs/facebook-page-canvas-setup

As for the other 2 WP examples, those blatantly violate Facebook's Terms of Service. While what they do is easily implementable, we wouldn't recommend it at all for the following reasons:
1) It violates rule IV.1)

You must not incentivize users to use (or gate content behind the use of) Facebook social channels, or imply that an incentive is directly tied to the use of our channels.

Facebook Platform Policies
2) You can see the effect of this on the demo site for the plugin below:
tyler.tc/devpress/2011/03/wordpress-like...before-reading-post/
When you click the Like button, it doesn't Like the page automatically, like it should. Instead, a "Confirm" link comes up, which when clicked, creates a pop-up stating "Are you sure you want to Like this?". That's all done by Facebook in an automated way, because they're detecting that something funny is going on (either through Unlikes, Spam reports, or general scanning of the page). This could lead to -all- Like buttons on your site being changed to the 3-step process (not good) or your entire site or application being banned (really not good).

For the reasons above, we can't help you implement the 2nd thing you were looking for.. but again, for Facebook Page Gates, we've got you covered, as that's covered under a different policy and completely do-able without getting in trouble.

Hope that helps!
Alex

Just tried the Like button on the page below, and it won't even register the Like click:
fblikelocker.com/

Not sure if that's a temporary bug, or a Facebook block, but my guess is definitely the latter. Not sure if you tried it or not.

Alex

No problem. We help how we can, and always try to make sure our users are on the right side of Facebook's Terms of Service.

Good luck with your site, and please consider leaving a rating and review for JFBConnect, or our support, on the Joomla Extension Directory. It's certainly not required, but very appreciated:
extensions.joomla.org/extensions/social-...ook-integration/7215

Thanks,
Alex

No, you can't lock your website in any way based on Likes.. either from your Fan Page or from a Like button on the page itself.

Hope that helps,
Alex