Just in time for the summer hol's. :)
Stars aligning for June Ivy Bridge Mac launch alongside Mountain Lion « Ars Technica
It's official! Mountain Lion and Mountain Lion Server will be released next month. They will cost $19.99 each (~£15.49 inc. VAT) and you can upgrade directly from Snow Leopard too.
Pricing & Availability
OS X Mountain Lion will be available in July from the Mac App Store for $19.99 (US). Mountain Lion requires Lion or Snow Leopard (OS X v10.6.8 or later), 2GB of memory and 8GB of available space. For a complete list of system requirements and compatible systems, please visit: apple.com/osx/specs/. OS X Server requires Mountain Lion and will be available in July from the Mac App Store for $19.99 (US). The OS X Mountain Lion Up-to-Date upgrade is available at no additional charge via the Mac App Store to all customers who purchased a qualifying new Mac system from Apple or an Apple Authorized Reseller on or after June 11, 2012. (Source)