Echoing an ancient and oft-derided excuse for the trains not running in the UK, Mayor of London Boris Johnson quipped yesterday that it wasn't the "wrong kind of snow" but rather the sheer volume of the white stuff that led to the collapse in transport infrastructure yesterday in the capital.

And just as there are many types of snow, there are likely to be multiple options for cloud computing, the new IT paradigm that is currently gusting toward us.

Take the view of IBM's Ric Telford, IBM VP for cloud services. The weather meant that Telford was unable to present his views at a London cloud conference scheduled for today, but he took the trouble to spell them out over a telephon conference link. Telford sees three approaches being taken by corporations in response to cloud computing.

First will be the conservative, risk-averse crew who go on as if nothing happened and maintain the status quo.

Second will be the "private cloud" adopters that take lessons from the cloud model by delivering highly virtualised, dynamic services that support chargeback processes, but keep systems in house.

Third will be the application-specific cloud service providers like Salesforce.com, Amazon.com or IBM's own Lotus software unit, delivering applications such as CRM, email, storage or some other capability.

The elephant on the table (or, perhaps, absent from the table) here is the lack of an all-embracing cloud provider that removes infrastructure from IT shops, transporting everything externally to become an internet-delivered, outside-the-firewall consumable.

On this, Telford is unapologetic, noting: "I don't see it, any more than client/server replaced the mainframe."

This view is of course anathema to cloud market bulls like Nicholas G. Carr. But 20 years ago there were plenty of bulls predicting the demise of 'dinosaur' mainframe technology. IT history tells us that old technologies don't die or even fade away but peacefully coexist for years and even decades with the latest and greatest things.