Upcoming Windows Phone "Mango" update details.
WinRumors.com has compiled a list as well which is pretty complete and has video of alot of it too. Check out their page at:http://www.winrumors.com/windows-phone-7-5-mango-feature-list-and-demos/
EDIT: Added some additional features that were mentioned at a later time.
Bing Audio: Think Shazam, but built into Bing and we bet of course Zune Marketplace. Country support is initially limited to the U.S., Great Britain, France, Italy, Spain and Germany.
Bing Vision: A full blown image scanner using your camera. It can detect, identify and search using barcodes, Microsoft Tags, QR Codes, CD’s, DVDs, Books, and text using OCR (see here for history)
Turn-by-turn navigation: “voice guidance during driving directions” (we heard about this awhile ago)
SMS Dictation: Using Microsoft's TellMe service, you can use voice-to-text for SMS messages by tapping a microphone near the bottom
East Asian Language Keyboard, Handwriting and Dictionary Support--[we saw this mentioned a few days ago]
Improved SkyDrive sync in Office hub - adding Word, Excel, and PowerPoint sync support. Each document type will now be indicated by the color of the tile:
Bing Image Search, Bing Vision, and Bing Audio – besides Bing Vision and Bing Audio as revealed earlier this morning, it seems like Bing will now feature Image Search as well.
Windows Live Messenger integrated in People hub – as we have predicted earlier, the Chinese developer confirms that Windows Live Messenger will be integrated in the People hub. You will be able to directly IM someone on your contact list.
Lync client (aka Microsoft Office Communications Server) - coming in the Mango timeframe
EDIT:Added more features that were leaked. May 15, 2011
Windows Live Messenger, Facebook chat and AOL Instant Messenger all integrated under Messaging--and remember, we heard this is rumored to be a dual data/SMS system, making it really reliable even when your connection is not. Your presence as well as your friends are displayed in the People Hub dynamically.
Office 365 and Skydrive built into Office hub--'nuff said
Group Messaging: currently there are some nice 3rd party apps that do this, but the ability to have pre-defined groups to message to will be now native, allowing to create quick groups for Family, Work, Friends, etc. This will work for Email and SMS.
Artist art on Lockscreen: This is very cool, especially those with Zune HD players. What this does is pull down the Zune/Artist artwork of your current selection and plays it in a marquee/banner fashion on the screen. It currently does this on your Zune desktop/Xbox (play some music and wiat a few mins, you'll see). Evidently, in WP7.5, you can do this on your phone, making the Zune HD/Windows Phone distinction even less. This was always an awesome thing on the Zune HD, so we're glad it's being brought over.
Xbox gets a facelift, including 'sync' option (potentially for online-game play). We first reported this back at MIX11, so now it's confirmed.
Native Checkins are coming e.g. Facebook Places.
Visual Voicemail will use Open Mobile Terminal Platform (OMTP)
Battery saving features/options (under Settings)
WiFi Hotspot support, uses Network Communication and Information Systems (NCIS) technology
EDIT:Added the info from TechEd about the business side of things May 16, 2011
Pinnable email folders: Pin a folder to the start screen for quick access. This could be an email folder for a specific project, from a specific group or person (like your boss), or an RSS feed you’ve set up in Outlook.
Conversation view in email: Emails in your inbox are organized by conversation, bringing replies to a thread into a consolidated view so it’s faster and easier to stay on top of the conversation.
Server search: Search your email server (e.g. Exchange Server) for older emails no longer stored on your phone, giving you ready access to all of your mail.
Lync:(previously mentioned in the post) Lync Mobile brings the Lync experience to Windows Phone customers by delivering Unified Communications capabilities, including instant messaging and the ability to see the presence of your co-workers. The Lync app will be a free download from Windows Phone Marketplace and will be enabled with support from your business organization.
Complex (alpha-numeric) password support
Information Rights Management
Support for access to hidden corporate Wi-Fi networks
EDIT:Added two more pieces of info May 17, 2011
Smart DJ - Found on the ol' Zune HD, it's described as thus "If you have a Zune Pass, you'll hear a mix of music from your collection and from the Zune catalog if you're near a known wireless network. Otherwise, if you don't have a Zune Pass or if you aren't near a known wireless network, the Smart DJ mix will just include songs from your own music collection.". Basically it rivals iTunes Genius and is something us Zune'ers have been wanting for awhile. (For a good 'versus' article, see Gounce's iTunes vs Zune piece).
Disable the camera shutter sound - pretty self explanatory, we can finally disable the ever so loud (and annoying) camera shutter noise. Hooray for spy shots!