A minor system software update for PlayStation Vita will be released today. It’s mandatory, and takes the firmware up to version 2.05.
Sony have said that the update improves system stability during the use of some features, although haven’t said what those features might be.
However, it’s apparent that the update blocks recent attempts to circumvent the Vita’s PSP mode security – the UNO workaround is gone, for example. Also removed is the ability to access the PSN without running the latest firmware.
So, really, it’s a security update.