It's a good week for Yahoo! as it appoints Marissa Mayer - previously Google employee number 20 - to the role of CEO. However, things aren't as cheery at Research In Motion, which has been ordered to pay over $147 million in a patent case.

Meanwhile O2 UK is recovering from a network problem that left around a third of its customers disconnected for almost a day.

Mark Bridge writes:

BlackBerry and bad news seem inextricably linked at the moment. RIM’s CEO admits he’s “not satisfied” with recent company performance and warns of challenging times ahead... and then the company is hit by a $147 million dollar damages order for patent infringement.

Mind you, Research In Motion wasn’t the only mobile company bringing disappointment into the mainstream news last week.

Vodafone Ireland and Three Ireland have agreed to set up a 50/50 joint venture company to share their physical network and site infrastructure across the country.

The deal, which has been rumoured for a few weeks, will see the two companies sharing around 2000 sites. As a result, Vodafone and Three will be able to reduce purchasing costs and potentially increase network coverage.

A new UK virtual mobile network called Samba Mobile is promising a mobile broadband service without any running costs.

Customers pay £2.99 for a SIM card plus £2.00 post & packing and then watch video ads to ‘top up’ their account with credit. A 3G ‘dongle’ will be available in the future.

The GSMA, the trade organisation that represents the interests of mobile operators worldwide, has announced a new scheme to help consumers understand and manage their data usage when abroad.

24 major network operators have agreed to implement a number of measures to help customers who are using their mobile phone abroad, reducing the risk of ‘bill shock’ when they return home.