Just the rules, now in hardback.

[Cammerz]

As we all know there have been two choices when it comes to the 40k rulebook; you spend £45 and you get the full hardback book which contains all the rules, a good deal of background and a miniatures gallery. This measures in at 11" by 8" by 1.5" which is quite big and heavy for those who want to go to a tournament with their army, codicies and rulebook.

The other option was of course the mini-rulebook contained in the Dark Vengeance box which contains only the rules sections and is considerably smaller but could only be purchased with this set or on ebay.

But now there is a third option;
http://www.games-workshop.com/gws/catalog/productDetail.jsp?catId=cat440161a&prodId=prod2160089a

It costs £30, 33% less than the large rulebook. It's hardback so maybe that'll stop pages from falling out through overuse, I'm not sure.
It's small, it has three bookmark ribbons so you can gain quick access to various useful sections and if you want you can get this version on your tablet for about £25.

Overall I think this is a good move from GW, albeit a little expensive, but we're getting used to this now.
Having already bought the large rulebook and the mini-rulebook I don't see myself needing this right now but if the trend continues across to Fantasy and in future editions then I can see myself getting something like this.

[Warptide]

Yeah, the option is nice. I have a printed out PDF of the rulebook but if I decided to go to a GT i'll probably end up picking this up. The extra bookmark ribbons is nice too 

[InsaneTD]

That sounds bloody useful. I might look at picking one up.