Microsoft announced today the availability of the Silverlight for Windows Phone Toolkit (August 2011) add-on for Visual Studio, a set of controls that developers can use to take advantage of new Windows Phone 7.5 ("Mango") features. Or as Microsoft calls it, the Windows Phone 7.1 SDK.

I may never get over Microsoft's bizarre and unnecessary naming conventions (the OS is version 7.1 but the product is marketed as version 7.5), but no matter: The Silverlight toolkit looks interesting. New features include:

LongListSelector has been rebuilt and redesigned to take advantage of the new smooth scrolling and off-thread touch input support in Windows Phone 7.5. This is a buttery-smooth control for showing lists, including grouping and jump list support.

MultiselectList control enables multiple selection for easily working with lists of data, similar to the Mail app’s capability.

LockablePivot adds a special mode to the Pivot control where only the current item is shown (often used with multiple selection).

ExpanderView is a primitive items control that can be used for expanding and collapsing items (like the threaded views in the Mail app).

HubTile lets you add beautiful, informative, animated tiles to your application, similar to the new People groups in Windows Phone 7.5.

ContextMenu control has been reworked: performance improvements and visual consistency fixes.

ListPicker now supports multiple selection.

RecurringDaysPicker lets your users select a day of the week.

Date & Time Converters localized to 22 languages. The converters let developers easily display date and time in the user interface in one of the many styles found throughout the phone’s UI, from a short date like ‘7/19’ to relative times like ‘about a month ago’.

Page Transitions have improved performance for a more responsive feel.

PhoneTextBox is an early look at an enhanced text box with action icon support, watermarking, etc.

All error messages and interface elements have been localized to all of the supported languages, making for a great experience for users around the world.

Additionally, this new version of the toolkit includes many bug fixes and address customer issues, according to Microsoft.  For more information, check out Jeff Wilcox's blog post about the toolkit.

And Microsoft, please. Stop using the name Mango and refer to this thing by its real name.