In case you hadn’t heard, 2006 is the 250th anniversary of Mozart’s birth, and classical music organizations the world over are falling all over themselves to pay tribute. So you might expect New York’s newly rejuvenated Mostly Mozart festival to be throwing the biggest party of them all, and you’d be right, but organizers are taking the unusual path of viewing Mozart through the lens of contemporary society. As part of its tribute, Mostly Mozart has commissioned four new works, “three of them ‘inspired’ by Mozart.” Throw in a Peter Sellars staging of a Mozart opera, a dance interpretation of the master’s piano works, and “a digital art installation tied to the Jupiter Symphony,” and it should be anything but a dull summer in New York.