Linear Video Editing Software for Mac?

Vilorman asks: "Everyone knows that there is tons of linear video editing hardware out for Windows and Mac. There is even quite a bit of stand alone linear editing software for Windows. There are all of these Firewire DV input/output boxes on the market but where is the software for them? We've got Final Cut Pro HD and DVD Studio for the Mac but that's all non-linear. Where's the linear stuff? I want to be able to take live video into my Mac and superimpose text over video or images over video and then send it right back out using the standard Firewire video I/O box that I already have; but I want to do it live on the fly, not in post-production where I have to ingest an hours worth of video and then print it back to tape. I know it can be done but where is the software for making it happen?"