I've read that both Microsoft and Apple have agreed not to sue each other in court.

That's convenient, but I don't think they made the same deal with Google (Project Astoria, the Android variation).

Imagine how well it would go over for Google if they started a copyright suit from the position that they heavily argued against in Oracle.

I'm not saying they wouldn't (or even shouldn't, since they lost the case), but I'd be amused as all get out. And it'd prove what we all know deep down: Google's position will always be whatever is the best position for Google.

Personally, I find it more amusing that you speculate a situation that hasn't happened, and has no precedent from Google's history, and then use that to confirm a speculation which "we all know deep down" :)

Well, I said "it'd", which is short for "it would". As in, it would confirm, if they did.

Can Oracle sue Microsoft?

No definitely not. It's not their code. They can't sue for others without their cooperation. And Apple doesn't need Oracle to fight their battles.

Wouldn't this be translating one API to another, versus implementing an API as in Oracle vs. Google? Wonder if that makes a difference.