I've never bought into the argument that "x" is around the corner, so don't buy now.
There is always something around the corner. To me, you should always evaluate what you have, get the best idea you can about what kind of performance gain you would get, and then consider your finances. I do this regardless of what is "just around the corner." There's always something just around the corner.
IMO, this is a great time to get a near top of the line processor. You can actually get an AMD cpu and board that performs within a few percent of the fastest thing out there for under $200 total. That's amazing. And by Intel standards, you can do similarly well with Intel (though not quite as cheap, but comparable.)
You can buy cheap now, and your $200 - $300 investment will be overshadowed in 6 months. Or you can wait, buy the new technology when it comes, and it will be overshadowed 9 months later. Or you can wait till the new technology is cheap, and then there will be something else just about to come out.
The cycle is always there, and it rarely significantly changes (one exception was the Celeron 300a which clocked to 450 - but that's a rare exception).