Microsoft published resources for developers who need to mock up an application UI for Windows Phone 7, Check it below:
- UI Design and Interaction Guide for Windows Phone 7 provides detailed information about UI elements and controls, UI system behaviors, and interaction model for touch interface
- Windows Phone Design System - Codename Metro. A visual explanation of the inspiration behind WP design system codenamed Metro, seven areas of WinP differentiation, and the Red Threads that're principles Microsoft used to guide experiences built into WPhone
- Design Templates for Windows Phone 7 is a collection of 28 layered Photoshop template files that can be used to create pixel-perfect app layouts, to help guide UI development, or to pitch an idea. These design templates showcase many controls part of Windows Phone Developer Tools Beta. They also include examples of controls part of WP, but aren't available as a part of WPDT. These additional templates are included to help designers & developers maintain a consistent look & feel across apps for system controls that developers wish to mimic. Templates in download: Application Bar & Application Menu, Buttons, Check Box, Context Menu, Date Picker, Dialog Boxes, Edit Control, Hardware, Icons, Keyboard & Input, List Picker, List View, Panorama, Panorama Backgrounds, Picker Box, Pivot, Progress Indicators, Quick Jump Grid, Radio Button, Reminders, Slider, Start & App List, Start Tiles, Status Bar, Theme, Time Picker, Toast Notifications, Toggle Switch.