Facebook, the world's biggest social media website, started selling stock to the public on Friday, with its initial $38 share price edging above $40 in the first hours of trading.

Facebook’s chief executive, Mark Zuckerberg, signaled the start of trading on the Nasdaq exchange in New York by remotely ringing a bell from company headquarters across the continent in California.

The team behind Android photo sharing application Lightbox is being hired by Facebook, with the exception of creative designer Giles Peyton-Nicoll who’s remaining in the UK. The service will continue to run for a month, enabling its millions of users to download their pictures until 15th June.

Lightbox co-founders Thai Tran and Nilesh Patel say they plan to open-source portions of the Lightbox code and publish it online.

This week’s podcast from The Fonecast takes a look at the European Commission’s new roaming charges before talking about the rest of the week’s big stories, from Facebook to free messaging.

You can listen to the programme on our website audio player, via iTunes, by using our RSS feed or by downloading the MP3.

It's been another busy week for the mobile industry, with European roaming charges, Facebook applications, Yahoo's CEO, mobile payments, free messaging and financial results all hitting the headlines.

Mark Bridge writes:

As summer approaches, so the media’s interest in mobile phone roaming increases. Once again, the maximum price of calls and texts when abroad in Europe is falling – but this year there’s something different on the horizon. The European parliament has just approved the EU’s plans to introduce a price cap for mobile data... and in a couple of years’ time we’ll be able to choose a completely separate network to help cut roaming costs.