Is iTunes Transitioning To The Cloud?
In November, iTunes launched the web based iTunes preview and now they've added song previews to the site. Apple is using Quicktime to offer song samples encoded at 44.1 AAC 300+ kbits per second.
For now at least, you can only access iTunes Preview through the iTunes Charts on Apple’s website or via any link generated from the iTunes Store’s copy link feature. The later feature was designed to encourage artists and websites to link back to the iTunes store