Please, provide a way to backup the texts.
Or, at least, provide a API access to the texts to allow developers to implement an application for SMS backing up.

Please provide developer platform support for bluetooth data transfer via SSP (Serial Port Profile). There are many bluetooth devices (e.g., medical devices, automotive, etc.) that we need to connect to.

This is an outctopping from the Native SDK suggestion (http://wpdev.uservoice.com/forums/110705-app-platform/suggestions/1755203-native-sdk). Please use this suggestion to vote and comment on your want/need for Qt support on the Windows Phone platform.

There... I said it. Allow native code (maybe sandboxed like in newer versions of Chrome) for better code usability. The 1st party apps are written in native code, then why not let us do it? If the apps behave bad you are free not to approve the app!

Been hearing this one a lot, and i'm sure a lot of other developers could use this as well. But it would be great to allow applications with push notifications to display an icon on the lock screen just like email/messaging. Even though its convenient to simply unlock one's phone and check the live tile, it'd be even easier if they didn't even have to unlock their phone at all to see if they have something important going on. In the future, this could be really useful with messenger clients when socket support is added, twitter, google voice, etc etc.

A cloud-connected device is essential for a mobile device. This means giving app developers the ability to automatically backup data currently stored in IsolatedStorage to the user's Live Skydrive. If the phone is lost or damaged, the data is easily recoverable.

This would help in creating screenshots for the marketplace. While this is easy enough using the emulator, it is difficult to simulate some features in the emulator.

My country has banned facebook and twitter, which means i need use vpn 2 connect facebook.

By providing in-app payments you allow the developers more options for making money.
Hey..the other guys are doing it!

Currently advertising funded applications is only available in the US. Please make this available to all supported countries.

it would be great to have the possibility to kill apps directly through the multitask screen(hold back button) instead of click+quit apps individualy.

Its usefull to access to be able to write on Calendar and contacts. For instance the Qanvas app would be able to create an appointment on the calendar, or an app that could add the events and birthdays to calendars like the facebook, or a birthday app.

For contacts it would be possible to integrate another contact info directly on persons hub to apps like Skype or Voip. The same idea as the extras funcionality on Zune or Bing Search.

Currently, when developing a alarm clock app, there is no way to tell if the user has his phone set to vibrate only, so a soundeffect set by the user is played even if he has set his phone to vibrate. I find this very confusing, even though the builtin alarm clock behaves the same way.
This would also be good to have for games, so when you launch a game in a quiet environment not all heads turn the user's way :)

Modify the email launcher API to add an attachement

I would like an experience more similar to the iTunes/iOS backup/restore.

If something goes wrong with my device and I hard reset or receive a replacement, I want to be able to simply plug it into my computer (or better yet, sign in with my live id) and have the option to restore *ALL* the data, apps and settings.

Please add full support for UPnP 1.1 / DLNA for third-party applications - perhaps even DPWS for potential future devices. The phone as a media / device controller is growing in popularity (ex: Sonos controllers).

It would be great to have Google + in People HUB, so we can easily sync our Google + account with Live and Facebook in the Hub. Every day many and many people are opening Google+ and leaving Facebook. So, Microsoft, don't be out of space and time. Make it real.

Live tiles are what separates WP from other platforms and providing developers free minimal Azure instance to host systems to support these notifications would increase use of Live Tiles and introduce more people to Azure.

SIM-Toolkit is essential for many users around the world. In Estonia we use PKI based authentication for everything and without SIM-Toolkit we cant use Mobile-ID to pay in bank or sign documents.