WP7 is missing following features:

1. Copy and paste text.
2. Preview of back button stack.
3. Socekts.
4. Battery api.
5. Camera - movie api.
6. Silverlight integration with XNA.
7. Exposed MAC address of WIFI.
8. Tile tap and hold option to unintall the app.

There are rumors that Copy and paste will be fixed on February. Will see.