Currently Windows Phone 8 supports only NDEF formatted NFC tags. It's not possible to NDEF format blank tags, lock or unlock existing tags.
I bought once pack of NFC tags on eBay, but they were not NDEF formatted, so I had to find a way how to format them. I found on Twitter a guy with NFC equipped Android phone and he formatted these tags for me. Windows Phones should be able to do this as well.

It is great that you now can write to the calendar database but there is not any API for change or delete an appointment?

It would be really a good idea if we could use the FindAllPeersAsync method( or something similar) to get a list of all discoverable devices within wireless range.

Please add support for Bluetooth Low Energy and Bluetooth 4. This will allow the development of applications that can support existing standard accessories and solutions across platforms. iOS and Android supports BLE. The WP8 hardware supports Bluetooth 4, but the software on WP8 does not allow the use of BLE.

An option to choose between vibrate on keypress or sound on keypress
I love to type with vibrating keypress

Android supports text-to-speech and vice versa without online connectivity. This is great for dictation. Please add this feature to Windows Phone.

In http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206968%28v=vs.105%29.aspx , default lock screen can't change.
plz allow change in xml, thx.
BTW: Like bing app background, it can change.

It would be cool if the developers could see how many times their App is viewed. For example, my app is viewed 1000 times, but only downloaded 1 time. If this is so, i can maybe change the story and the images so people would understand my App better.

When there's only a slow network connection available, the Bing Maps control freezes when the user hits the hardware back button. This delay can take up to 30 seconds after which it can even happen that the app is terminated by the OS.

The bug has already been documented in multiple forum threads:

Thread 1
http://social.msdn.microsoft.com/forums/en-us/wpdevelop/thread/03acca68-41f8-4cc6-b1a3-6a09463125bb

Thread 2
http://social.msdn.microsoft.com/Forums/en-US/wpdevelop/thread/7ab6a447-8b0a-431e-993e-a38bd67509da/

I have released several versions of my app throughout its life cycle. Knowing how many users are using which version of my app would be great.

Something like: %10 is using version 1.0.0.0, %20 is using version 1.1.0.0, %70 is using version 1.1.1.0 etc. on my dashboard.

Making app certification faster.

Our company has no windows computers and all development is based on GPL'ed or other source available code base. Now it seems impossible to do anything with windows phone?

Currently we have only access to the name and the type of an account.
If a user has defined sub calendar, we are not able to recover the name and the color of the sub-calendar.
This prevent us from creating a good display of appointment. We are not able to distinguish appointment from the different sub calendar.
For one account, we can only defined one color for ALL sub-calendar

Create an graph control.
Why not creat an native powerfull graph control to WP ? Actually we have to look for third parts control...

We expect xna 5 for all platforms, with better 3 d and multimedia content

Just a small issue: When I work on my WP app the phone often times out and locks itself. When I hit the Play button, more often than not, I get the error message that I must first turn on and unlock my phone.

The phone in question is not password protected and has a connection with my PC already (I can browse the phone with Explorer).

It'd be great if Visual Studio automatically turned on & unlocked the phone upon deployment - if needed.

Business man uses two phones for their works and private.

Nowadays, there is a lots of Dual-Sim supported phones. Android support dual-sim architecture on their OS level. But WP8 doesn't.