When Google unveiled the SDK for Android 4.0, the first thing we noted about Ice Cream Sandwich is that the default "Holo" theme would be baked right in at the OS level. The company has gone a step further today, explaining that the inclusion of the theme will be required for any Android 4.0 device in order to get access to Google's suite of apps, including Android Market.
Unfortunately, while this is a nice step forward for consistency, Android skin haters shouldn't proclaim victory just yet. The Holo theme is simpy a set of UI widgets and design elements that developers can use to build apps. While that means that 3rd party developers will have the option to design widgets and apps with the theme, it most definitely does not mean that Google is enforcing usage of the theme on anybody, least of all manufacturers. The Holo theme will be the default theme for any app that doesn't specifically request the device's default skin, which will mean that the look and feel of TouchWiz, Sense, and the like won't go as deeply into 3rd party apps unless developers want it to.