The user 'zilli' in the Pixelmator forums wanted to know how (here is the thread) to follow this tutorial from psdtuts. I tried to recreate such a button in Pixelmator and here is the result:
And here is my file for download:
Telephone Keypad ButtonNote: You can copy, share and edit this document as you like. You can even use it for your own project. It would be nice to be informed and/or to be mentioned.