Good spot by +Nick Butcher that in ADT 17 Support Library the GridLayout is back-ported to API 7 and there are new tools for helping manage your Up vs Back navigation (see <sdk>/samples/android-15/AppNavigation for example)
Android Developer Tools

Revision 17 of the SDK Tools and the Eclipse plugin is out today.

It brings a lot of new features including more Lint rules, support for custom views with custom attributes in libraries, a bunch of new emulator improvements, and additions to the Support Library.
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