So apparently Chaosium's new direction will be a Runequest 4th edition, referring to the 4th edition of the RQ game done by Chaosium (but still really a 7th edition for everyone who's been with the game since MRQ). The 4E version will however use RQ2 as the springboard/base from which it builds. I admit, this intrigues me.
Meanwhile, Design Mechanism will continue to support Runequest 6, which will get a name change.
I absolutely agree with Akrasia that this could fragment the base, but I'm not sure what can be done about that....we have exactly the same problem with D&D, which is fragmented between five (well, seven really) editions of the base game plus countless OSR retroclones and inspired D&D-alikes, so the fact that Runequest will have two coterminous editions....not to mention stuff like Legend and Renaissance....strikes me as business as usual for this hobby, which tends to be recursively derivative to a fault.