We already have all of the technology we need for a spacefaring society, and probably have had it for some decades. Our economy is stuck in a local maximum, where there is no short-term economic benefit to going there.
For example, the original Orion project had a means of traveling to Saturn in a year. (Using nuclear bombs to power a spacecraft.)
The various studies on space colonization are also interesting. T.A. Heppenheimer summarizes some of them (in particular, the famous Stanford Summer Study) in his book "Colonies in Space."
Interstellar travel is another thing entirely, though.
Read Zubrin's _Entering Space_ for details.
http://www.amazon.com/Entering-Space-Creating-Spacefaring-Ci...
For example, the original Orion project had a means of traveling to Saturn in a year. (Using nuclear bombs to power a spacecraft.)
The various studies on space colonization are also interesting. T.A. Heppenheimer summarizes some of them (in particular, the famous Stanford Summer Study) in his book "Colonies in Space."
Interstellar travel is another thing entirely, though.