From what I've seen of Cavium, I wouldn't describe them as general-purpose CPUs, though they are nice for their own niche. I don't think anyone in the west has gotten hands on anything except press releases of ShenWei systems, so it is unproven as far as I can tell. If it is so great why was the Chinese National Supercomputer Center trying to get their hands on Xeons so badly to upgrade Tianhe? :P
Edit: Along the lines of Cavium, you might want to check out Tilera. They aren't exactly general-purpose either but they are more so than Octeons, and have respectable single-thread performance from what I've seen.
It's a multi-core MIPS64 processor with PCI, USB, and do on. Remember that MIPS has been used in everything from embedded to SGI Origin supercomputers. Quite general purpose. Cavium's addition is SOC, lower power, and accelerators.
Regarding ShenWei, it was used in supercomputers. It's probably real. What jumped out is that it's probably stolen IP from Alpha CPU and had high watts. So, not as power-efficient or legal as they'd like was my guesss.
Re Tilera
I read the MIT RAW Workstation papers where all that began. ;) Yeah, it's pretty cool but that's the one that's limited purpose. It's like an overlap between vector processors, FPGA's, and multicores. I dont know who all uses them but I did find a 100Gbps network tap and NIDS that used 3 Tileras for its muscle.
I knew of a company that was testing Tilera for 4G basestation/RNC equipment, not sure if that ever panned out(I think they use Cavium + FPGAs now :P). I think Tilera is basically dead as a standalone product now after all the acquisitions, they'll probably be folded into Mellanox's interconnect acceleration wasteland and never be heard of again.
Sad as there was so much hype back in the RAW days of where it would be applied. Then, it became a commercial activity of a stingy company that didn't foster a strong ecosystem. That effectively sealed its fate given DSP's, FPGA's, and GPU's were killing everything in their path if we're just talking energy/performance/price. Your prediction might come true.
Edit: Along the lines of Cavium, you might want to check out Tilera. They aren't exactly general-purpose either but they are more so than Octeons, and have respectable single-thread performance from what I've seen.