Straight from Microsoft Windows Phone developer platform team - Windows Phone Toolkit provides the developer community with new components, functionality, and an efficient way to help shape product development. WPToolkit releases include open source code, samples & docs, plus design-time support for the Windows Phone platform.

• Ensure you have Nuget version >= 2.1 for WP8 projects.
• Download WPToolkit Package on NuGet (Nuget is updated with latest binaries and localized resource assemblies)
• Download WPToolkitTestFx Package on Nuget for Test Framework
• Download source code and samples
• Release notes
• Discuss in the Developing for Windows Phone forum 

Components in #WPToolkit

• AutoCompleteBox
• ContextMenu
• CustomMessageBox
• DateTimeConverters
• DateTimePickers
• Effects – SlideInEffect, TiltEffect and TurnstileFeatherEffect
• ExpanderView
• HubTile
• ListPicker
• LongListMultiSelector
• Map extensions
• PhoneTextBox
• RatingControl
• ToggleSwitch
• TransferControl
• Navigation transitions
• WrapPanel
• LongListSelector for 7.x
• MultiSelect for 7.x
• Samples are included in the source code.

FAQs -

Q - I have WP8 SDK and I installed the NuGet package, it is still installing the 7.1 version of the toolkit assembly, or I get an error – “You are trying to install this package into a project that targets 'WindowsPhone,Version=v8.0', but the package does not contain any assembly references that are compatible with that framework.”

A – You have an older version of NuGet. Install the latest NuGet from www.NuGet.org . Close and restart all the instances of Visual Studio. Now install the package. It will install correctly. WP8 projects are supported from Nuget 2.1 onwards.

Blogs & Tweets

Official: Windows Phone Developer Blog
Executives: Joe Belfiore
Evangelists: Jaime Rodriguez, Pete Brown
Developers, Designers, Geeks: David Anson, Dave Relyea, Jeff Wilcox, Shawn Oster, Tim Heuer, Jason R. Shaver, Rohan Thakkar

Open Source