I am going to develop project based on ARM Cortex-M3 processor, how can I get started? Is there any example in C & Assembly programs?

To work on the cortex-m3 processors, you should meet the following requirements:
1. Software requirements: You should install an integrated Development Environment in your computer, such as Keil RealView MDK or IAR EWARM.
for Keil RealView MDK, you can download the evaluation edition or purchase the authorized edition from www.Keil.com.
for IAR EWARM, please visit to www.iar.com

In addition, I want to suggest a software to you, it is CooCox CoBuilder. It integrates plenty of drivers and components for users, so users can fully concentrate on the development of application software. please visit to www.coocox.org

2. Hardware requirements: you should have one evaluation board which is based on ARM cortex-m3 processor, and one JTAG Debugger for cortex-m3, then you can download flash and debug your programs.
for evaluation board for cortex-m3, please visit http://www.embedinfo.com/en/list.asp?id=39.
for JTAG Debugger, please visit http://www.embedinfo.com/en/list.asp?id=42.

Is there anyone show me some sample projects which has been used the arm cortex-m3 processors?

Thanks for liuing's help, now I have knew something about Embedded programming.
And also Thanks for coocox, from here I find many useful information and examples.

If you want to get more examples, from:
http://www.coocox.com/CoOS.htm

If you want to know how to begin with a tool, from:
http://www.coocox.com/CooCox_Builder.htm

I hope this will help you...

Please help me!

Commercial software products is indeed very tough, but for low-end users, the cost is the most important, I am more optimistic about CooCox a series of free products, expect them to do better in the future.