This is a great article on how an improvement of Google will allow them to continue to dominate for quite a long time!
Google Search has been recently challenged on four things by competitors Microsoft’s Bing, Twitter, Yahoo and Facebook:
Real Time Search.
Microsoft’s Bing proving to be something of almost an equal level to Google Search.
Partnership between Yahoo and Microsoft on Search.
Facebook’s interest in Real Time Search.
Google Caffeine is an attempt in the right direction by Google to answer to these challenges.