http://aycu08.webshots.com/image/35287/2005416824790529648_rs.jpg
New? This occured when I copied some text from a website and posted it into my email and was going to send it. the link was one of those "Top" ones.

Yes, it's probably new. The new Gmail uses the same WYSIWYG program as Pages and Groups, which already handled links this way.

it's new, with Gmail 2.0
and maybe useless for many of users.

I didn't noticed it before.. but it's nice, I like how it performs :)

this came with the new interface of gmail
somewhat alike to yahoo mail, but nice and handy feature

Isn't that there so you can test the link before sending the email. The worst thing with sending links is sometimes you send the wrong one but don't find out about it until one of your recipients sends you a reply.