The only thing is that Apple and Google aren't killing each other, at least not yet. Both companies are doing exceptionally well. Apple continues to have record years and I think the competition from google is only fueling their improvements to the iPhone. MS isn't even a factor at this point in the cell phone game and Google is doing well, but they don't really have the package or mindshare in cellphones at the moment (we'll see where things go, of course). I don't have any kind of smart phone at the moment so I have only played with the iPhone and Motorola Droid. Though when it comes time for me to get a new phone (in about a week or two) I will likely end up with a Droid or Eris because I can't get an iPhone on verizon, yet. If I could get one on Verizon I would, though.
I doubt google will ever even consider whatever MS has for a search engine a real competitor. Microsoft's biggest problem here is that they keep changing it. Google is just.. Google. It doesn't change much and that is why they win. Apple will never seriously compete in the desktop search space, but on phones they have a good reason to want to get into that at least a little and there is room for them there.
I think MS will continue to dominate in the OS space for the foreseeable future simply because most software is there and people/businesses are practically allergic to change. I would love for OS X to be even more prevalent but it will be a long time before we see even 20% of the market using it.
In the end, Linux wins.