I would like to know if I can use the thumb from Facebook for commercial use? I've seen it on a stamp (http://gizmodo.com/5561499/we-really-like-the-facebook-like-button-rubber-stamp), but is that legal to make if you're not Facebook?
There are two issues, copyright and trademark.
Copying the thumbs-up image exactly would probably be a copyright infringement (though not clear if Facebook would care...). However, designing your own thumb that looks similar would not. Facebook can't prevent other people from using a common thumbs-up image.
Because a thumbs-up image is so common, Facebook has a very limited ability to claim it as a trademark.
If you are using a thumbs-up image for a different purpose (e.g., something other than "like"ing) then I don't see a trademark problem.
If you are using a thumbs-up image for the function of "like"ing something without using the word "like, then it is probably still ok as I imagine that others did this before Facebook and others do it today.
If you are using a thumbs-up image for the function of "like"ing something and using the word "like" then it is a more difficult question. Personally, I don't think FB should be able to get TM rights for that, but companies like FB can be very agressive in protecting trademarks. I could see FB going after the rubber stamp maker that you mention.
Practically, absent a Gizmodo article about you, FB would probably never notice your use of a thumbs-up image (with or without "like") so you likely would not have a problem.
Facebook Brand permission !!!
If you want to use it - Visit this link https://www.facebook.com/brandpermissions/requests.php