Facebook recently redesigned its iPhone app and made it universal. You also get a little more control over links you share in status updates.
Now, after you paste the link, scroll down a little to see the thumbnail + URL embed that Facebook creates. If you don’t like something about the content Facebook automatically pasted into your message, tap anywhere in that space to expand it and reveal options for tweaking the link. As of this writing, you can get rid of the thumbnail or the link itself.
Strangely, you still need to manually erase the original URL you pasted if you don’t want it to clutter up your post.