Adobe updated a number of their programs on the Creative Cloud yesterday.
The new Photoshop CC 2014 installs alongside Photoshop CC and offers to transfer settings from Photoshop CC. Only some setting are transferred across (actions for instance) and others such as interface colour etc are not so be ready to tweak a little. If the worse comes to the worse you still have the older Photoshop CC to go back to so not too bad (and means you can play with the new features without compromising your stable working version).
Adobe have taken the opportunity in Lightroom 5.5 to now allow the updating of lightroom from the Creative Cloud Control Panel. Previously Lightroom could only be updated by using the Lightroom program to check for updates and them manually downloading the new version.
Unfortunately there appears to be problems with the new form of updating via the CC panel and Lightroom may fail to start when updated in this way.
Until Adobe fix this problem I suggest you download and install the new version of Lightroom directly via these links:
Adobe write some great imaging software but they are really rubbish at building cloud infrastructure. My assertion that Adobe Creative Cloud is not a robust method of delivering critical imaging software still stands.