Well it's based on, and looks just like Firefox but has Bittorrent built in and claims to speed up downloads. I am trying it and so far it's pretty good.
It's called Wyzo.

Before you continue to use this program, I would recommend a careful read of...
Should I continue using Limewire?

or any number of other such discussions.

All P2P will pose a threat to you...
for reasons that Kimsland clearly sets forth in the above discussion.
(Including the quote from Kritius)

But then... you probably know all that... just others may not.

Thats snazzy, probably won't ever use it though, downloading the torrent along with the actual file may slow down downloads for small files :P. Probably not, but I don't think the speed increase would be worth it.

I haven't tried it. Does anyone know what client it reports as? Because I think a lot of people that are serious with torrents are members of private sites, and most private sites have an enforced list of clients you can use. I would be surprised if this works on a lot of private sites.

Opera?

It seems quite odd that I (somebody who lacks interest for anything P2P) am aware of this,
http://www.torrentoolbar.com/ and the people interested don't? It isn't built into the browser, this one is just a toolbar you install on your browser...