Today Swedish Telia, as the first operator in the world, launches a 4g-network. American Verizon and Docomo in Japan will follow later. The 4g-net is only available in the central parts of Stockholm and Oslo at this point. Theoretically the so-called LTE-technique opens for a maximum speed 100 Mbit/second. Ericsson and Huwaei are the companies that developed the technique, which will allow for new services, like streaming HD-TV. The price for this kind of connection will be around 600SEK ($85)/month, Telia says, but the introductory price, valid until summer, is symbolic 4SEK (ca 50 cents [sic!]) - I assume this means one will have to sign up for a long term subscription.
Personally, I will probably not get 4G for a long time. I just cancelled my Telia 3G broadband a week ago, since I can now connect the computer to the internet with my mobile phone like any 3G modem.
Update: Wikipedia article about 4G