The big news circulating at the moment is the current 6th edition 40k rulebook is now listed as "no longer available" on the Games Workshop Website. The talk is that this is a prelude to the re-release or 7th edition of 40k. This would mark an unusual move for Games Workshop as to my knowledge, they have never recycled an edition so quickly.
In what was meant to be a new release year for WHFB 9th edition, hopes where dashed with the statement from the (now defunct) Games Workshop Digital Editions Facebook page when the iBooks version of 8th edition WHFB was released, stating that they would not release a digital book if it only had 6 months life left in it. And in more recent events, Games Workshop released the ebook version of 8th edition WHFB which went largely unnoticed.
Reports are coming in that Games Workshop stores have been requested to send back their copies of 6th edition 40k (unconfirmed), and local/independent stores have received a new stockist sheet with a large turnover of current/existing stock lines.
As far as the rumour front goes on what we can expect if this pans out, a new 7th (6.5?) edition box set will incorporate Blood Angels and Orks in the core set. As far as rules changes goes expect to see the integration of a lot of the peripheral rules and for another push to harmonise rules more in line with WHFB.
Rumours have gone as far as saying random charges will be removed (unlikely) and force organisation will have percentage caps introduced (likely). One thing for sure is if this does all pan out to be true, the loudest 1% will scream bloody murder to money grab much the the amusement of the other 99%. I for one will be interested to see if they can clean up the current mess that is 40k.