Where can I find style guide for metro UI for web applications?
I am interested in the Metro UI that microsoft has used for windows phone 7 for web. I see that their site microsoft.com has been done with metro UI recently.
I am looking for a style guide and resources that I can use to build a web app based on the metro UI.
Related: Windows Phone UI and Design Language on Channel 9 (video)
May you have a look at Jeff Wilcox' "Metro" Design Guide for Developers: http://www.jeff.wilcox.name/2011/03/metro-design-guide-v1/
This guide is not as extensive as the PDF provided bye @Jin, but focuses on some main aspects to consider, when developing WP7 Apps.
For a quick look, Jeff Wilcox's "Metro" Design Guide is good.
If you want to see an after-action report, Scott Barnes wrote about his experiences with Metro.
The comprehensive manual titled Windows Phone 7 Series UI Design & Interaction Guide is also available.
You may find the Channel 9 video helpful.
You may find this documentation from Microsoft helpful: Downloading design assets for Metro style apps http://msdn.microsoft.com/en-us/library/windows/apps/hh700403
Also, I created a simple Windows 8 Metro mockup PSD available for download here: http://dribbble.com/shots/301642-Windows-8-Metro-UI-Demo-PSD
Here's a list of metro-style websites for some inspiration: http://teusje.wordpress.com/2011/03/17/web-design-trend-metro-ui/
Also, you can take a look to this templating framework to create websites styled like Metro UI.
The OP was requesting resources and style guidelines, not a list of examples of Metro sites and an undisclosed link to your own site. If you're referring to your own site in an answer then it's not cool to pretend it's just something you found. If it's relevant then disclose that you have a site that answers the OPs question.
I found this article for an app I was working on: Everything You Need To Create Windows 8 Metro UI-Styled Websites