A patent scheduled for sale next month in San Francisco could threaten some of the biggest players on the internet leading Web 2.0.

Listed in Ocean Tomo's spring auction catalog as lot number seven, patent number 6,418,462: "Discloses methods allowing clients to perform tasks through a sideband communication channel, in addition to the main communication channel between a client and server".

In supporting documentation it is claimed that pretty much the whole of the web uses this method to operate AJAX-based applications. Google, Yahoo, Microsoft, Apple and eBay are identified as among those whose products "potentially" infringe on the patent.

Singled out are AJAX mashups including Google Maps and Gmail, and Microsoft "Live" - the latter being a broad and slightly nebulous category. Also in the frame are Amazon's S3 and EC2 and clusters from Microsoft, VMware and Oracle. eBay's Skype, Napster and Microsoft's Groove are also listed as potentially infringing on the patent in P2P.

The claim centers on the way AJAX uses background processes: "Most significantly, the patent is directed to the core concept fundamental to AJAX: extra data requested from the server may be loaded in the background, through an asynchronous data request channel, thereby ensuring that there is no interference with the display and behavior of the existing page".

Clearly if the claim is valid, the value of the patent - filed in 1999 and issued in 2002 - is substantial. It will be interesting to see who bids and what the new owner does with it. One possible option on the table is to prosecute claimed infringers, cashing in through the US courts.

Ocean Tomo auction president Andrew Ramer said simply in a statement ownership of this patent presented a "unique opportunity" to secure the existing development efforts and provide "long-term competitive advantage" for developers, internet companies and sites in AJAX and Web 2.0.®