ReWire is a software protocol, jointly developed by Propellerhead and Steinberg, allowing remote control and data transfer among digital audio editing and related software. Originally appearing in the ReBirth software synthesizer in 1998, the protocol has since evolved into an industry standard. (from Wiki)
I bought reBirth in 1998 and still have the box, it has both Propellerhead and Steinberg logos on it. 
Yes, I did.
Yep, me too.
Well I was surprised to find out.
Cleaning out my attic I found my original ReBirth box and saw the Steinberg logo on it, and wondered about the relationship between Prop and Steinberg.
I thought it would have been brought up in the forums more by people wondering about Rewire integration with 64bit.
anyway…
thats right until propellerhead and steinberg had a massive bust up and went their seperate ways 
old old news