What it did with Android could also be done to define home and portable consoles platforms.

There have been rumours about this for years, but the big difference is that now Android is succeeding, while before nobody really knew whether it would have made it or not.

An Android-like gaming platform could be implemented on PC's too, BTW, unifying the two worlds.

You have to look at motivation. The motivation to enter the phone hardware market is entirely defensive, I don't see them moving further into hardware unless they have to.

But actually Google doesn't produce HW, it released an OS and SW platform for smartphones, it could do the same with an OS and SW platform for gaming, recycling a lot of parts from Android, BTW... Just like with Android they wouldn't have to personally delve too much into HW, actually they'd provide tools and services to HW manufacturers. And the Holy Grail of unifying PC and consoles could really open unknown opportunities.

It would be a project conceptually similar to 3DO, with the difference that nowadays HW is dirt cheap, making things easier on the pricing front, and Google has many more resources to succeed where 3DO failed.

They are working on phone hardware at the moment, as a defensive move against iphone.

If they don't work on both hardware and software for a games console, they won't be a player at all.

Who's going to make the hardware if Google doesn't? Remember, Sony and MS both heavily subsidized the HW costs to reduce the price tag of their systems and hope to earn that loss back through game sales. And both MS and Sony make their own games which are the most profitable for them.

The only one I could possibly see using an Android OS for a gaming console is Sega and that's highly unlikely.

Yes, a possibility. But let's also not forget that for example Nintendo follows a radically different business model from MS and Sony, that Apple, should it try the gaming adventure, would follow a model similar to Nintendo's, but not totally equal, so just another business model that nobody devised before, or else that nobady was able to succeed with before, is always possible. Providing a royalty free platform and getting paid only for advanced dev tools and services (if wanted), while giving for free more basic tools, specifications and all the other technical infos needed, could attract both SW and HW producers, particularly indies craving for PC freedom and low starting costs, but higher consoles revenues. If Googles puts in the deal its huge advertising power, it could be one of the ingredients 3DO lacked.