Moreover, alongside innovative minnows like Gigablast, there are well-endowed whales such as Microsoft. Even if it failed to come up with any new approach to online searching, it could still out-Google Google by creating a server farm made up of a few million machines – it needs to do something with the $50 billion of cash that it is sitting on. The first glimpses of Microsoft’s approach in the search engine arena are not too exciting, but then neither was Windows, and look where that is today.

Also likely to be a major player in the search sector is Yahoo, which recently parted company with Google, and unveiled its own search engine. In its simplicity and overall design, Yahoo’s front end looks remarkably like Google’s, but the real challengers may be those that adopt quite different approaches.

Amazon is not a name that springs to mind in this context, and yet search has been a core technology for some time. In 1999, it bought Alexa, one of the most innovative Web search companies. More recently, it has added a feature called Search Inside the Book to its main site, offering the ability to search through the texts of many of the books that it sells. Now it has launched its experimental A9.com, which combines the latter capability with results provided by Google and other new features.

The arrival of Amazon upon the search engine scene with its full-text index of physical books supports a prediction by Microsoft Research’s Jim Gray in a recent Netcraft Interview: that alongside traditional search engines focusing on Web pages, other, more specialised sites will appear, including those that concentrate on different kinds of online data, currently inaccessible – what is sometimes called the “Deep Web”.

Another example of this trend is eBay. After all, its huge popularity depends crucially on the ability of visitors to find what they are looking for among the huge range of goods on offer – a kind of search engine for information about the world of objects. Perhaps an example of Web Search 2.0 has been staring everyone in the face for years.

Glyn Moody welcomes your comments.