I didn't know a thing about these "Complete Rules", and I can't find a thread that explains the whole thing. I'm kinda lost, help?
The announcement was sort of hidden in other threads - here is the relevant part of the press release:
August 24, 2010 - Poulsbo WA
Frog God Games, the successor to Necromancer Games, is pleased to announce that effective immediately, Mythmere Games, headed by award-winning author Matt Finch, will be joining up with the Frog God Publishing team to produce even more of the true old-school gaming resources that Necromancer Games and Frog God Games have always been known for.
[snip - me saying PR stuff]
As a result of this merger, Frog God Games will be publishing the Complete version of the old school, ENnie Award-winning Swords & Wizardry™ fantasy role-playing game, which will be released in November.
The Complete Rules are mainly just the 0e rules looking at all the supplements, so there is a thief class, ranger, paladin, etc. More optional material for order-of-combat is included, rules for naval warfare, and all the other additions mentioned above in the thread. Core Rules are still a supported game for playing the three archetypal classes, but lots of people wanted a more complete picture of 0e than the Core Rules provided. The Core Rules are admittedly an odd snapshot since they use only the WhiteBox classes, but use other "later" material that came from books with additional classes beyond the original three. The Complete Rules don't mix and match the time frames; it's all there.