ISS Flight Engineer T.J. Creamer has sent the first tweet from space. Did he use his pointy nipple antennas to transmit data back to Earth? No. According to NASA, he used the "ultimate wireless connection", which actually is quite clever.
The new network is called Crew Support LAN, a software update that allows astronauts to personally use the internet as they will use it from their own home. This can only happen during times in which the ISS is transmitting data to the ground stations at high speed, using Ku-Band communications. However, it's not as simple as firing up Firefox from space.
The astronauts get into a remote desktop program on their laptops to control a desktop computer on the ground. So, while the computer on the ground access the internet openly, but the ISS's astronauts don't really "touch" the internet with their laptops. A simple, but very smart way to avoid security problems on board the space station.
This connection is purely for personal use, as the crew already has e-mail, IP telephone, and videoconferencing. According to NASA, the personal use "will be subject to the same computer use guidelines as government employees on Earth." So no porn or torrent for the space dudes. [NASA]