Technology is advancing. Some of these technologies will--to some extent--be paradigm-shifting (farming, industrialization, electricity, TV or Internet). This effectively puts a limit on the timeframe for which you can still make any sensible prediction of, say, human culture or something. Now, the premise is that the speed of advancement of technology is increasing (exponentially or otherwise). From this follows that the timeframe for predictions is shrinking. Believers in the technological singularity pose that this timeframe is shrinking non-asymptotically, and therefore will reach zero at some finite point in time. This point in time is called the Technological Singularity, and by definition, we are completely unable to predict what happens after this point in time.
To put this more simply: suppose I were to ask you to predict if the moon would have civil war within the next week. You'd answer with a VERY high degree of certainty "Of course not, because they're couldn't plausibly be enough people on the moon by next week for their to be a war, and even if their was a way nothing in the current state of the world suggests that their will be living on the moon by the end of next week." If I say 50 years, it gets a little more plausible - maybe by then spaceflight becomes cheaper and colonization of the moon (on a small scale) becomes feasible. You could answer No with high certainty, or Yes with pretty low certainty. If I were to say 500 years you couldn't be certain either way - maybe humanity's dream of spaceflight collapses as we enter another dark age; maybe the moon gets colonized and people argue over territory. The key is that we make predictions based on our current understanding of the world and how quickly things change - not that much happens in a week, but a lot could happen in 500 years.
The idea behind the Technological Singularity is that once that happens, so much stuff could happen in any given timespan that any kind of meaningful prediction about the future of human affairs becomes impossible. Once we're in the Singularity, for instance, a wi-fi brain network of students in Argentina on intelligence boosting drugs could produce an entire new field of mathematics while you're sleeping, which is applied by the Berkeley-Microsoft Xbox Live Protein Stability Computation Grid to invent a protein that synthesizes a high-powered fuel out of topsoil and salt water. Because of advances that make the internet more efficient at circulating useful information, every business-minded biologist in New Euromerica switches on his Synthavirus Gene Lab and transmutes a tub of yeast into a tub full of yeast that makes cheap fuel out of dirt and salt water. An architect realizes that the aluminum bars in every persons' prefabbed home could now be used as a very powerful railgun, mentions this to an engineering forum, and within an hour the brain network in Argentina (who has now solved mathematics, and is quite bored) comes up with a way to quickly and turn any house into a rail-gun launched spaceship. By this time P&G has switched from biowarfare to energy production and is making a killing selling 1.2 jigga-amps to every house in the world.
One Hundred and Seventeen, the premier magazine for hip youngsters just out of their first century, runs an article on space fashions mentioning this new development, causing people all over the world people to press the "Reconfigure" button on their houses to convert them into space ships and take off for the moon. Unfortunately, the Neo-Feynman uses the new math and lucky guesses to crack every encryption algorithm in the world, revealing every deep-cover troll used by the Department of Motor Vehicles, leading Senator Chuck Norris, /b/-Canada, to call for a purge of the hated DMV trolls. Firefights break out all over the world, as roughly 50% of the population is a DMV troll. The fighting extends to the flash mob on the moon, which manages to form a Lunar Government only after all the next-gen fusion bombs have already been launched.
At this point you wake up, and are very, very confused as to a) where all the topsoil has got to, and b) why there are 500 people dressed as 1920's business men dueling with power drills in your back yard. Then a large radioactive chunk of what was formerly the moon falls on them, and you are merely left to wonder where all the top soil went.
So if somebody asked you if any given event was going to happen tomorrow, the best you could have done would have been to flip a coin.