Blogoscoped reports that Google has expanded their Public Data Onebox functionality and now you can see the Internet penetration rate for population of any country. All you need to do is search for “internet users in cyprus” (or use your favourite country). Currently, it reports Cyprus having 38% of the population connected to the Internet. And that sounds just about right.
The country with the highest Internet penetration rate that I know of is Netherlands. Google reports it having 86.8% of population connected. Which also sounds just about right.