Well I never thought I'd say this but; I've been really inspired by the Windows design team.
Yeah I said it. Windows, as in Microsoft Windows has taken a huge leap forward in it's design language. This article, on their blog, gives a good overview of the philosophy that drove the design of the new Windows 7 phone. If you've ever designed a UI or you've been tasked with creating a design guides, then I recommend you take 5 minutes to read it.
Hopefully this uncharacteristically intelligent approach to design finally marks a change in Microsoft product development.