Apparently Microsoft took to heart the criticism that almost every review of Windows phone 7 had – that the applications had to restart every time that the lock screen was disabled. As we noted, developers do have access to disable the app from closing when the lock screen is enabled but they’ve gone a step further to make it easier to enable this (and now the user does not need to be notified as long as requirements are met). Here are the new requirements:
The minimum battery life of the phone must be greater than six hours while the application plays audio under a locked screen. If an application is not playing audio when the phone is locked, the application must remain idle while the phone screen is locked.
Applications that do not play audio under a locked screen: The minimum battery life of the phone must be greater than 120 hours while the application is running under a locked screen.
One other change deals with music and the goal is to let you keep listening to your music and not the app:
When the user is already playing music on the phone when the application is launched, the application must not pause, resume, or stop the active music in the phone MediaQueue by calling the Microsoft.Xna.Framework.Media.MediaPlayer class. If the application plays its own background music or adjusts background music volume, it must ask the user for consent to stop playing/adjust the background music (e.g. message dialog or settings menu).
On the memory side they have also reduced the amount of RAM that an app can use (which should make apps faster, less laggy and easier on the battery while loading faster). They’ve also extended the ability to upload photos to third party sites that can integrate right into the photo viewer lie native apps.
You can get more details from the Windows Phone Developer Blog.