A few more details have been released on the above now, and as far as comic books go it is indeed a massive upheaval.
DC is the oldest, longest established producer of superhero comic books in the world. Indeed their actual name, DC comes from Detective Comics which is the title that introduced the world to Batman, a few weeks after Action Comics brought us Superman; both iconic characters.
Their announcement is that as of September this year all titles in their main universe line are being cancelled, to be relaunched with 52 new monthly comics, 13 regular issues a week, all issues starting from #1.
Most titles will have new creative teams, with many of the characters being updated for the modern market. To some degree this is understandable - the characters are 70 + years old and are perhaps dated, but... as I've mentioned above, this is not the first time that DC have done this. It's not even the second.
It's rapidly becoming a marketing ploy to drag readers in, but slowly elements of the old start to creep in, and the one thing that shows the full history of the comic, the number will be mourned, talked about then re-emerge in a few years time.
Although it is hard to make any judgements at the moment some of the previews are starting to look worrying (but as I say this is only from the previews so there may be more to see that explains things).
A few years ago in there crossover Zero Hour, DC retrofitted their timeline and it looks as tough they are going to do the same here. Some characters are being completely relaunched 'new', others are being brought back, and yet others are continuing as though nothing has happened. All well and good.
There are going to be two (there generally always are) Superman titles, but the Superman in one wears jeans and a t-shirt, the other the traditional costume. How it all fits together remains to be seen.
It is obviously a major event... but one that seems to be little more than the latest marketing ploy. How long it will last is anyone's guess.