As hinted at back in February, Last.fm has been trawling around looking for a buyer and today it found its harbour in the form of a US media giant. The ‘social music’ site has been bought by CBS Corporation for $280m (£140m). This is less than the earlier rumour, but still the largest-ever buyout of a UK-based “Web 2.0” site. The site was founded in the UK five years ago