You may remember a few months back now that Apple unveiled a new system in which it used a web-based interface to show song information for an individual iTunes URL, before you were physically transferred to the actual iTunes store itself. The move came in sync with the iTunes store re-design which saw the store become more streamlined overall, with a cleaner, crisper interface. Until now, these new web-based 'Preview' pages have lay dormant, offering no real purpose other than to provide necessary links to albums and individual tracks on the iTunes store.
Today, Apple has reportedly enabled studio 30 second previews of all tracks in it's current iTunes catalog to work in-browser. Mac Rumors are reporting via GigaOM that these previews are encoded in 44.1 KHz AAC format at 300+ kbps, and playback is issued via QuickTime.
The move falls in line with Apple's recent acquisition of the online music streaming service Lala, which could see Apple move it's entire current catalog online, possibly offering all-you-can-eat subscription based plans in the future.