Yeah now that I think about it multicore CPU's are probably a huge scam. I bet a $200 GPU could run threaded stuff (with some help from Cuda and ATI's version) 100 times faster (literally) than an $800 iCore.
Not true if you look at processor architecture. It's a trade off: A GPU is great doing complicated floating point calculations and other tasks that can be easily parallelized (cracking WAP keys, for example, or other cryptographical problems with thrive on floating point and large primes).
However, Google's MapReduce (the way the search engine works, more or less) wouldn't be able to run on these beasts, since it's essentially really, really fast data look up. For that, you need a general purpose CPU (that's how Google does it, for example), or other specialized hardware. But who owns a PhysX board (It's to physics engines what old VooDoo was for 3D acceleration)?
And multicores don't just provide a benefit to one multi threaded application, but you can run multiple single threaded applications at the same time. For example, I could run two instances of Dwarf Fortress without performance loss (assuming all else being equal).
I still think it will be a fad, 'cause someone will probably find a way to make multicores run serially, that might seem like a silly argument, but it would fulfil the need for serial processing power, whilst a GPU already takes care of multi-threading.
Somebody said the same about personal computers, too: They are a fad, and only interesting for businesses.
EDIT: No matter how many cores you throw on a cpu, you're still gonna be better off running some stuff through the gpu, and to put all those extra cores on, you probably have to reduce the frequency.
The first part is true (see above), but not the second part. The only time you lose a bit of performance is, if a thread has to be shifted from one core to another core. However, multicores are, essentially, a proven technology: Servers and workstations (like the SPARCStation, or the Mac Pro) use multiple CPUs for ages now.
Multicore simplifies architecture (shared L2 cache, shared memory pipelines) to lower cost (at the trade off that you lose maybe one or two cycles of processing power, which doesn't matter with cycles in the 2 000 000 Hz range).
The trick is to exploit the benefits of multicores, and it will take a while until software developers are able to solve that. Concurrency is hard, but necessary to fully exploit the hardware. It's akin to the advent of structured programming languages, or object oriented programming. Takes a while to catch on.
To answer the OP's question: I doubt that DF will be multi-threaded any time soon (at least as a playable version). Multithreaded apps are a whole different approach to program, and require major(-ish) reworkings of how DF does things currently.