Interesting recent developments in academic computer science.
randomwalker: In the academic world, the semantic web is pretty much taken for granted. Curiously, it appears that people in the real world have been saying for so long that the semantic web will never happen that they have failed to notice that has already happened!Look at this diagram: http://en.wikipedia.org/wiki/File:Linking-Open-Data-diagram_...
 All these datasets have already been interlinked and are available for you to use. This is the linked open data approach (http://en.wikipedia.org/wiki/Linked_Data) The opposite approach is to use data from a single already-interlinked source through an unified API, exemplified by Freebase (http://freebase.com), which is more straightforward but perhaps offers less control. I've found these resources invaluable in more than one project that I'm working on, and every hacker should at least keep abreast of what is available so that you can use it if you need to.