According to arstechnica blog, the internet has used 90% of its IPv4 capacity as of January 2010 (see what is an IP address here).  The increase to 90% from the previous number the blog reported, 81%, came in about only a few weeks.

The Internet community has come out with a solution (IPv6) with greater range of numbers to use from, however the blog suggested that the IP usage is moving much faster than anticipated and there might be a problem in the transition.

Read more about the topic here here.