Microsoft showed off a number of new features planned for Windows Phone "Mango," the major update for the smartphone platform due this fall, at its MIX 11 event in April. These were primarily features aimed at developers, with the company keeping new user-facing features close to its chest. News is starting to leak of just what those user-facing features are going to be, and there's plenty of them.

The Windows Phone Dev Podcast posted a bunch of screenshots purporting to be of Mango. Their podcast wisely warns that in these days of Photoshop a little skepticism over such leaks is wise, but all the features shown are plausible, and consistent with glimpses of the user interface seen elsewhere.

The Bing application is gaining eyes and ears. Bing Vision offers barcode scanning, OCR, QR tag recognition, and the covers of books, CDs, and DVDs—all familiar features to anyone who has used the iPhone Bing application. What's not found in the iPhone application is Bing Audio: indications are that the Windows Phone application will be able to listen to music and tell you what it is—going head-to-head with Shazam. This is in addition to the existing speech-to-text features already available in some markets.

Speech-to-text will be included in more than just Bing. The screenshots show a dictation feature for text messages, allowing messages to be spoken rather than typed. With increasing awareness of the dangers of using a phone while driving—not to mention legal prohibitions—dictation support is a natural extension of the existing voice capabilities. What we can't tell from the pictures is how broadly this support will be available; currently, the voice support is limited to only a few markets, something that will have to change for this to be a major feature.

Speech also figures in the updated Bing Maps application, which will apparently offer a "voice guidance" capability, giving a hint that the operating system will include full-blown turn-by-turn support. Although Mango will offer limited multitasking to third-party applications, turn-by-turn isn't one of the supported scenarios; building the feature into the built-in Bing Maps software would make that functionality gap far less important. The maps will also include compass support, so that north always points north, rather than always pointing to the top of the phone.

Marketplace, which already saw performance and organizational improvements in the "NoDo" copy-and-paste release, is going to be extended to include support for podcasts, and possibly even video podcasts (the word "podcast" is bad enough; "vodcast" is too horrible to even contemplate). Podcasts will be publicized through Marketplace, and the phone will handle both subscription management and downloading.

More features were shown off by Liveside.net. Though Windows Phone launched in a number of markets around the world, it was restricted to those using the Latin alphabet; Windows Phone 7.5 will be marketed to a larger number of markets, and to that end, will contain support for some non-Latin scripts. The leaked pictures provide confirmation of this, with East Asian keyboard support, text entry, and dictionary entries/autocorrection.

One of the more glaring omissions—at least to IM junkies—was a lack of built-in support for Windows Live Messenger. There's an official third-party application, but this is lacking in several ways. It doesn't integrate with the People Hub—in spite of the contacts lists being shared between the application—and doesn't run in the background (though it does use push notifications). Reports are that in Mango, Windows Live Messenger will be integrated with the People Hub, doing away with the need for a separate application. There are also claims that messaging will unify SMS and with Windows Live Messenger; send a message to someone, and it'll use the best available mechanism to get it to them.

This description of the messaging system sounds not a million miles away from the unified messaging that HP's webOS includes. That's not the only Windows Phone feature that will have been "inspired" by webOS; the multitasking system will use a kind of zoomed out view of all your open applications to switch between running tasks, just like webOS, and LiveSide.net is reporting that each browser tab will be selectable directly from the task switcher—again, just like webOS.

With the API improvements announced at MIX combined with the interface and feature improvements leaked so far, and the confirmed inclusion of Internet Explorer 9 and Twitter integration, Windows Phone 7.5 is already shaping up to be a major release. And it's likely that there's more still to come; there are persistent rumors of NFC support, for example, though nothing confirmed so far. The full story should become a lot clearer in a couple of weeks; Microsoft sent out invitations today to a press event on May 24th, at which Microsoft will "lift the curtain" on the next major release of Windows Phone.