How to pre-populate the Facebook status message through an URL similar to pre-populating a tweet?

That actually violates the FB TOS:

Policy Violation: Pre-fill the user message parameter with any content the user didn't enter themselves, even if they can edit or delete that content before sharing. This applies to posts, comments, photo captions, and photo album captions.

https://developers.facebook.com/docs/apps/review/prefill

Facebook doesn't want you to tell users what to say.

use the FB sharer - though it's supposed to be deprecated for a year or so it still works just fine. just add a link to a page or forward your user to this url (change the www.myDomain/path/ part):

Forward to:

http://www.facebook.com/sharer.php?src=sp&u=http%3A%2F%2Fwww.myDomain.com%2Fpath%2F

or add link like that:

<a href="http://www.facebook.com/sharer.php?src=sp&u=http%3A%2F%2Fwww.myDomain.com%2Fpath%2F">Share on FB</a>

be aware that all info that's presented for your page can be set via META tags which must be present on the page that was passed to the sharer.php. You canNOT change the title, image and description via some other variable

that's about as lightweight as it gets - hope it helps

Update: see http://davidwalsh.name/facebook-meta-tags for a good tutorial on the meta tags

Update 2014-01: the API is no longer deprecated... lol