There's a growing perception (not sure I share it yet, but can't ignore either) that Mac development is taking a back seat at Apple. I know they target the latest and greatest unexploited biz niches and more and more on being a global provider in those niches - and that it's working spectacularly - but they're also making inroads in the still huge PC market, which, given their margins, cash stash, etc., they have the resources to keep increasing sales and market share.
So they may be hard on it, but sounds like over a year after their "interim" OS release of Snow, which was to be the clean out the old and provide the foundation technologies for future editions of OS X, we're not likely to hear a peep about a new cat being readied to leap out of the bag any time (or year) soon, nor any iWorks (or iLife) '010, etc. which have been annual releases up to now.
Maybe the point releases are considered sufficient incremental advances since there clearly won't be a Win 8 for years. Maybe Apple's seeing the whole PC market as over the hill. Maybe the back rooms are up to their armpits at work on a sizable makeover that will bridge the functionalities of iDevices and Macs in new ways. Maybe...... ???