Kudos to the author for providing an exact licensing term, quoted as follows:
Personal Use: You can use this for any personal (non-profit) project or to experiment with Photoshop, etc. without any attribution necessary (but if you want to throw some kudos, it would be much appreciated).
Commercial Use: You must contact me BEFORE it is used in any commercial project in any way and the design must be attributed to me.
Sharing: You can share this with others by linking them back to Dribbble, but you may not host or distribute this PSD on your site.