No iTunes Match access

iTunes 10.5 doesn't yet allow users to sign up for Apple's iTunes Match subscription service, which will scan your entire music library and replace tracks with high quality files from Apple.
It'll cost $24.99 in the US, but Apple has yet to agree deals with UK record companies to bring iTunes Match to the UK. Those deals are not expected to until spring 2012 at the earliest.
That service is expected to launch stateside in the next few weeks.
If you want to upgrade your iPhone, iPod touch or iPad to iOS 5 you'll need iTunes 10.5 so we'd recommend you download the 100MB+ file now in order to save yourself a little time on Wednesday.