This is a good question that unfortunately cannot be answered yet.
Look at the picture on the right of this page:
http://en.wikipedia.org/wiki/Logistic_function
And then the picture here:
http://en.wikipedia.org/wiki/Exponential_function
Note that, if you were a person walking along both curves through time, there is no way to discern between the two curves until you reach the inflection point shown in the Logistic curve (also called S-curve). There is some evidence that the exponential curve will not hold - 45nm microprocessor fabrication came slower than 90nm and up. At the same time, some scientists argue that there will be no inflection point and the singularity will occur.
I believe that if a tech singularity is going to happen, it will happen through the creation of seed-strong-AI; in english, artificial intelligence that can truely learn and discover beyond what it is distinctly told to. Unfortunately this also marks the point where humans become inferior to robots (terminator anyone?).
Still I think a tech singularity is highly unlikely. I expect to see technology growth rate slow down in the next few years. The logistic graph occurs far more in nature than the exponential curve. This begs the question - is technology natural?