Lightworks is probably the first (?) truly cross platform NLE, running on Linux, Windows and (soon) Mac OSX. So although its exciting to see the demo above at NAB 2013 of Lightworks on Mac it obviously doesn't look any different to any demos on Windows or Linux, because, you know, its the same program.
You can use 5K R3D files in the current version, otherwise its 2K for resolution. 4K is coming in Lightworks 11.2 (11.1 out end of April) it will also have new ingest features, curve based color correction and AJA support.
There will always be a free version of Lightworks and the pro version of Lightworks is a minimal annual cost (£40/$60). Lightworks is hoping to come to a public beta on OSX in the next several months (a few months to alpha and then a robust beta a few months after that) – or possibly at IBC in September. So the wait continues. For a fuller mac demo check out the video below from Newshooter.
If you're wondering why you might want to use Lightworks at all (compared to Premiere Pro, Avid or FCPX) then it will be worth downloading the free version and giving it a go. Also check out this article on the Redshark News site from editor Fran De Souza.
If you're interested in learning more about how Lightworks functions check out the recently released 'Sharkbites' tutorials series, which are mirco tutorials on specific features within the NLE. Further tutorials will be added over time. If you can't wait that long have a rummage in the Lightworks category.