When it comes to birthdays, the internet is a bit like the Queen –­ it is fortunate enough to have two.

For some purists, the birth of the internet came on 2 September 1969 when a connection was first established between two computers on the US Arpanet network. But for populists, the 40th birthday came last week, on 29 October, the anniversary of the first exchange of data between those two systems.

For most of us, 40 is a milestone that generates much reflection, and a redefinition of what we always meant by “middle age”.

For the internet, 40 is certainly a marker of a growing maturity, but any mid-life crisis is felt far more acutely by those established industries that have seen their business models radically changed by the online revolution.

While downloads –­ both legal and illegal ­ – transform the entertainment industry, and online advertising decimates areas of publishing, every other sector should be assessing the pace of change and wondering how it will affect them.

There will be no getting away from it ­ – 40 years is just a passing moment in a revolution that will yet transform business and public life more than even the industrial revolution.

As more big public sector IT projects struggle, there can be little doubt that the fragmented, open, collaborative nature of the web is the likely architecture that must and will underpin public service delivery through technology.

And as the financial services sector tries to avoid the scale of change that many of its recession-hit consumers demand, you can be sure that at some point, new models of banking that provide greater transparency will emerge, enabled by the opportunities and experiences of the internet.

It is almost a cliché already to say that when it comes to the internet revolution, you ain’t seen nothing yet. IT leaders would do well to reflect on the innovations that they, as the corporate enablers of internet business, must adopt to keep their organisations at the forefront of inevitable change.