Per the wiki here: http://code.google.com/p/imageshackapi/wiki/ImageshackAPI

I should be able to do a POST or GET to http://reg.ImageShack.us/setlogin.php to determine if a user is registered or not. I can successfully make a GET request and get a proper response with XML content. If I make a POST request to the same location using the same parameters, I get a 200 response code but the content is always empty.

I would expect to get the same content back from both request types.

you are right, sorry, URL in document is incorrect. Please use http://my.imageshack.us/setlogin.php instead, sample:

curl -F xml=yes -F login=b2b745fce6edf3055805b07709ac34f5 http://my.imageshack.us/setlogin.php

yes b2b745fce6edf3055805b07709ac34f5 example@imageshack.us 20 sena

I've updated documentation