As a brand Apple dominate the smartphone market. The iPhone is the single highest selling handset and Apple sell more phones worldwide than everyone apart from Nokia. Looking at Android as a whole you have more sales, sure, but the brand loyalty is with the manufacturers. People are buying HTC and Samsung handsets, not "Android" handsets. I notice this a lot being a Windows Phone user; people don't seem to distinguish a difference between my HTC Trophy and the HTC Android handsets. To them both are HTCs. Likewise, little to no connection seems to be made across manufacturers. HTCs are HTCs, Samsungs are Samsungs. Android doesn't seem to register, or is only a vaguely understood term. These are problems for both Google and Microsoft. For Microsoft, people seem to have a grasp of what Windows Phone is, but they don't identify it in partnership with handsets. For Google, their OS has become absorbed by the HTC and Samsung brands, the Android brand itself isn't actually all that well recognised or understood. As such both companies are quite vulnerable within the market.
Microsoft already have a possible solution to their woes in Nokia. If they can make the Nokia and Windows Phone brands synonymous with each other then Windows Phone will become a lot more visible on store shelves. It will be far easier for consumers to identify the product as it won't be lost in a sea of HTC/Samsung/LG Android handsets.
Google's problem is the opposite. Android handsets are extremely visible, but the Android brand isn't. The brand loyalty (for the most part) is to the manufacturer, which could potentially cause headaches for Google should a viable, customisable alternative appear. The HTC brand and Sense UI can be carried to other platforms (Meego?). With Alien Dalvik even Android's apps can go elsewhere. If the consumers are following the manufacturers then Android's place in the market is by no means secure, especially if the manufacturers are given reason to go elsewhere (customisation, freedom, control). Using the Meego example, Sense could easily make it's way on to that platform. Over time it could potentially become superior to the Android version, yet provide a user-experience that's similar enough for consumers to not notice the transition between platforms. Android could be slowly phased down if it's within the manufacturer's interests to do so. Google need to make people aware of Android and the benefits it brings. If they make people want Android phones, make them request to see phones with Android on them in the shop, then they will be hard to oust. Android needs to be the desirable brand otherwise it could become lost in the market somewhere down the line.