The release of
Marvin for iPad and of
iPad 3 with Retina screen were the
top 2 IT events of 2012 for me.
It appears that the release of Marvin for iPhone and of iPad mini with Retina screen might become the top 2 IT events of 2013.

OK, let's make it top 3 by also including the
Mailbox app, which has completely revolutionized the way I'm handling the
hundreds of email messages I receive
every day.
(And yes, I'd classify the original release of iPad mini last year, with an obsolete screen and at an inflated price, as one of the top
disappointments of 2012.)