The newspapers and internet news sources (the BBC, for example) have been full of comment about Bill Gates’ decision to step down from the helm at Microsoft over the next couple of years. Comments about it being "the end of an era" are probably quite appropriate, and Gates’ timing is impeccable.
Gates was the architect of the software giant’s domination of the operating system and office software market, based on selling packaged and increasingly feature-bloated software that sits on users’ local networks and/or PCs.
He is stepping down as new software architectures are beginning to challenge this approach. Software-as-a-service (SaaS) applications, Google-hacks, etc, are often slimmer, aren’t reliant on particular operating systems or browsers, and are increasingly delivered via the internet, so the focus is increasingly on managing system infrastructure and maintaining data and functionality availability (moreover, these "disruptive technologies" change key company perspectives such as revenue recognition – sure, the turnover of a SaaS business may not be increasing dramatically, but look at the future order book… investors and analysts will need to change how they assess the value of businesses, including Microsoft).
It is significant, I think, that Ray Ozzie (one of the originators of Lotus Notes and then Groove – now Office Groove 2007) is Gates’ annointed successor – as one of the key evangelists for online collaboration and document sharing, he has good credentials to help Microsoft retain a key role in the changing IT market (and Wired agrees).