Passing php variables to Facebook Application Tab

Are you able to send php variables to a application in a tab (in facebook)?

I have built a system which sends a wall post to a friend, which includes a link with a php variable in it. This variable needs to be processed by the app, but I cant work out ho开发者_JS百科w to (or if I can) do this.

Yes, you can pass URL Parameters to an iFrame Tab App.

Pass the parameter: http://www.facebook.com/MyPage?sk=MyApp&app_data=any_string_here

Receive the parameter: $app_data = $signed_request["app_data"];

See more: http://forum.developers.facebook.net/viewtopic.php?id=92661

I think this is a duplicate of the following question:

Facebook Application Tab -> External Linking with PHP

It does not seem to be possible to pass URL parameters into a Facebook application that is in a Tab. You can do it on the Application page however.

Edit: as per the answer below, this behaviour has changed. Details here: http://forum.developers.facebook.net/viewtopic.php?id=92661