From the latest report of MobiThinking we found out some key stats that might help you re-considered having a mobile website. Also the European Interactive Advertising Association provides extremely interesting information:

• There are 5.3 billion mobile subscribers (that’s 77 percent of the world population)

• Half a billion people accessed the web from a mobile device in 2009. Usage is expected to double within five years as mobile overtakes the PC as the most popular way to get on the Web.
• 25% Americans access the mobile web each day.
• By 2011, over 85 percent of new handsets will be able to access the mobile Web. Today in US and W. Europe, 90 percent of mobile subscribers have an Internet-ready phone.

• Europeans spend an average of 6.4 hours per week on mobile Internet
• 71 million users access the Internet via a mobile device averaging nearly 1 hour of mobile connection per day

Source: MobiThinking & EIAA