Google launched its long-awaited rival to Apple’s iTunes service on Wednesday with a free music streaming service and cloud-based locker capable of playing tracks through web browsers or to Android-based mobile devices.

The company has signed licensing deals with three of the four big music labels – Vivendi’s Universal Music, Sony Music Entertainment, and EMI – but has yet to agree terms with the fourth, Warner Music. It has also signed hundreds of independent labels and will have the rights to stream as many as 13m tracks.

The service would initially be limited to the US, Google said. The company said it had to date activated 200m Android devices worldwide and is adding 550,000 new devices a day – although it declined to specify US sales.

A majority of consumers are uncomfortable with the amount of commercial messages they see on social networks, a large global survey has found, even as Facebook and Google+ introduce more brand advertising to their online communities.

About 57% of social network users in developed countries – and more than 60% in the US and UK, which are among the world’s largest advertising markets – do not want to engage with brands via social media, according to a new study by TNS, a market research firm owned by WPP, that polled 72,000 consumers in 60 countries.

“Misguided digital strategies are generating mountains of digital waste, from friendless Facebook accounts to blogs no one reads,” TNS said.

Tablets, it seems, are becoming pretty popular these days. So a new study from Knowledge Networks further should open some eyes:

Adult tablet owners age 18-64, the study found, spend almost four and a half hours on the internet each day compared with three hours for non-tablet owners. Interestingly, not all of that difference is made up for with the 55 minutes they spend on the internet with the tablets themselves.

Companies in the entertainment and food and drink sectors are buying the bulk of adverts on Facebook, indicating the social network is being used increasingly as a tool for brand messaging, as opposed to direct sales, a recent report revealed.

The volume of advertisements bought by companies in these sectors, as well as those in beauty, automotive, and games, rose 117% between the second and third quarters of 2011, stated a report from TBG digital, an independent marketing company specialising in social media.