First review of tri cores: http://www.xbitlabs.com/articles/cpu/display/phenom-x3-8750.html
This is a very good review, since it also includes dual core scores from both AMD and Intel.

It's not surprising that tri-cores don't make much sense at current performance and price levels. I guess AMD has to do something with defective Barcelona cores...

Pricing:
AMD Phenom X4 9750 (2.4GHz) – $215
AMD Phenom X3 8750 (2.4GHz) – $195
AMD Phenom X3 8650 (2.3GHz) – $165
AMD Phenom X3 8450 (2.1GHz) – $145

Dropping one core at 2.4GHz saves a whopping $20!

Overall performance is very poor. In gaming benchmarks, all new tri-cores lose often even to K8 based dual core, and are very far behind E8400 dual core Wolfdale. Even in multithreaded benchmarks like x264 encoding, Cinebench or Maya, fastest tri-core Phenom X3 8750 is slower than dual core E8400, while Phenom X3 8450 is slower than Athlon64 X2 6400+.

Overclockability of X3 8750 was decent: 2.4GHz->3.1GHz, but then again E8400 also overclocks very well and has significantly lower power consumption with much higher performance.

Interesting power consumption numbers from Anandtech:
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3293&p=9

2.4GHz tri core Phenom consumes significantly more power than 2.4GHz 65nm Core2 Quad...

Ah, fuse off a core to get TDP down enough to raise clock speed, I get it.

You could also fuse off a core if it ran slower than the other 3...

Hmm, it would be fun to figure out which core/cores were the fastest and have the OS schedule processes and dynamically adjust clock speed accordingly. :)