Sony and Box have just announced they have extended their previous partnership until the end of 2013, so Xperia users will continue to receive free cloud storage space.
The previous agreement between the two companies should have ended on December 31, 2012, which is why Sony and Box agreed to extend it further. The partnership between Sony and Box was announced in 2011 and was available for one year.
Under agreement between the two companies Xperia smartphone and Sony tablet users free 50GB cloud storage for life, by signing-up or accessing existing Box accounts from their devices before December 31, 2013.
Keep in mind that this offer is only available for Sony Xperia smartphones including and released after Sony Xperia X10, but not for Sony Xperia X10 mini, X10 mini pro and devices with Android versions prior to 2.1.