It has nothing to do with the Open Source part and everything to do with the "triumph" part. Android devices are selling very well. Its competitors couldn't care less how it's built or by whom. Their response is the same regardless: they use every tool in the shed to not only make themselves better, but to act as a drag on their competitors.
Open has a lot to do with it - Android is a great OS by itself but because it's free, it has hurt RIM, MS and Apple's profits quite a bit. Hence why they've banded up and decided to throw everything they have at it.
I think you meant Nokia not Apple. Apple's profits have been world beating and they sold pretty much every iPad and iPhone 4 they could make for the last year.
Which is not to say Android isn't a threat to Apple, clearly it's the largest threat, but just that it hasn't seriously affected Apple's profits.
Android is only a threat to Apple's profits, but not its market. There are things that vertical integration provides which are unique and of value to a decent sized population. For instance, it is hard for Motorola to replace a handset which is past its warranty to build brand loyalty. Or hardware only manufacturers cannot provide free or cheap training sessions which may be seem inscrutable to us, but are meaningful to a lot of people.
Apple's and Google's models are pretty orthogonal, and there is space for both. Sure they both compete aggressively, but it's everybody else whose models are in a mess.
Since they have been mostly supply constrained I would say not a whole lot more. It's a valid question though, they might be able to extract a larger subsidy from carriers.
I expect Apple would much prefer iOS to have a duopoly with WP7 than with Android. Open platforms lead to messy disruptive innovations that can quickly dislodge established players.
If you believe the idea being thrown around that Microsoft makes more on Android patent shakedowns (licenses) than it does from its own mobile OS, then no, Android has actually helped Microsoft.
