Update:
It looks like this event will be a limited time, and some of it is good for all levels. The world bosses are tuned for endgamers, but I'll get to that in a minute.
When you go to Tatooine, there'll be a new crashed starship in the Dune Sea. There's an [Area] quest there, where stepping into the area gives you the quest. You'll have to kill some infected crewmen, and avoid getting the 'lightheaded' debuff. There's a vaccine you can buy from any meddroid too.
If you have the lightheaded buff for 10 minutes, you'll get a 2nd debuff for another 10 minutes. If you're not cured by then, you explode, infecting anyone around you.
(you also get extra Rakghoul DNA credits but I'll also get to that).
Completing the area quest gives you 'Rakghoul DNA credits', which can be spent at a jawa vendor in the area for different colored weapon crystals (green and black, special customizations for companions (they make your companion look all spooky) and a rakghoul minipet.
There's an optional quest that takes you out to eastern Tatooine tracking down a crashed escape pod with a bunch of Sand people. There's a lot of codex entries if you do this one.
Also, I need to follow up on this investigation but there's another crashed escape pod in Mos Ila/Anchorhead that leads you on a twelve step quest for another (different color) rakghoul pet. Since it's a limited time deal, this'll be the only time to get one. I'll let you know what I find out.