Promising, and I agree with you on all accounts in regards to GPUs/vFPGAs when power is cheap.
The most important element for me is a solid ROI.
BTW, what country is the data center located?
In regards to penetration testing do you mean renting out the processing power of password cracking (Cracking as a Service)? Pre-computing Rainbow tables and selling them or something else? I've thought about both of these as options...
I'll be watching for an IPO.
I'll definitely try my best for a solid ROI. That being said, changes in price and difficulty, mining luck, etc. will definitely keep me on my toes!
The data center is in Washington state - the cool Pacific Northwest where hydro power is plentiful and in the right places can be quite cheap.
For renting out processing power, I'm thinking first of password cracking, but honestly I've got my hands full with my bitcoin mining in the short term. I'm planning to set up a test rig soon with backtrack and figure out an optimal configuration. Rainbow tables are an option too, but haven't really spent much time fiddling with that yet.