Besides the timeline, is there any other materials for Rogue Trader that mention these things?  And do you think we'll be getting rules for them in Battlefleet Koronus? 

I know I've seen fan supplements that added them, but there are no rulebooks containing them to my knowledge.

Fortinbras said:

No and I hope so.

I hope that they arent just Tyranids.

 This has been discussed a few times before

Here:

http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=123&efcid=3&efidt=409495&efpag=0#410737

Here:

http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=123&efcid=3&efidt=404023&efpag=0#404272

And here:

http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=123&efcid=3&efidt=364489&efpag=0#365813

The Boy Named Crow said:

House rule.  House rule.  And blatant speculation.  

I don't think, that they'll include them in Battlefleet Koronus, though it would be cool. They tend to not include too much epic stuff into the rulebooks, usually they just mention it in the fluff, leaving the ruling to the GMs. But I could imagine an adventure including a Void Kraken.

"Release the Kraken!"

What about disruption cannons? Are they effective against a Kraken?
(It doesn't have components, but maybe the dis. cannons can shock it or something)