The change in difficulty is a HUGE unknown variable in ROI calculations...as is the value of the bitcoin itself.

Would I advise somebody to drop $100k on a mining setup? Only if it's clear they have the ability to move $100k worth of used computers if they needed to.

It would feel the true opportunity in bitcoins is meta....an exchange, a service to facilitate purchasing of goods from sites that don't accept bitcoins, etc. It "feels" like this is an emerging market with many opportunities...but I feel like mining is small thinking, in terms of generating significant recurring revenue.

Here's an idea, figure out something you can profitably pay people in bitcoins to do, that can be done just sitting at a computer. You can't have a real economy without jobs, and right now about the only viable 'job' that pays in bitcoins is making bitcoins. It would have to be piecework because paying hourly would create an unnecessary administrative burden.

There are all kinds of bored-ass people sitting at computers who might be happy to e.g. proofread OCR, categorize images or write/summarize articles for money. Some are bored enough to do some of that for free but eventually anyone gets tired of that, look at how the Wikipedia model frustrates a lot of productive people into leaving. Whatever they make, even if they don't make a lot starting out as is the nature of piecework, can potentially increase in buying power if the price of bitcoins goes up. Additionally, the fact that all those people have bitcoins to spend furthers the goal of widespread use. You ensure quality by cross checking results and rewarding high accuracy/writing quality with extra bonuses.

Bitcoin is based on a solid algorithm, but is driven by a community that seems to seriously lack objectivness, probably because of vested interest into ever increasing exchange rates. I am not sure if they are not going to crash the whole thing out of blind and zealous faith

If I were you I would wait and see if the whole Bitcoin ecosystem does not collapse entirely in the coming days.

Maybe you can start by building one rig, and convince yourself that the profit is worth the trouble.
You should also make the experience of one or two difficulty increases, and factor the outcome into you profitability model.
In bitcoin denomination, you profit is going to decrease exponentially over time, so you will have to rely on a permanent and proportionnal (therefore exponential) increase of the BTC/USD exchange rate if you want to have a stable income in your native currency.

Now if you have alternate business models for your hardware, like creating a GPGPU cloud service or if you would like to help cancer research by running folding@home, then it's a different story.

I seriously doubt a few spammers on these boards had anything to do with pricing...

I sent bitcoins from deepbit to my mybitcoin.com account address. However i did not receive it. Is there something wrong.
i sent 1 Bitcoins

Suggestion:

What about creating sub forums in the newbie section

A newbie mining sub-forum would catch all the "what PSU do i buy" posts

A newbie> merchant forum to help new merchants

etc.

"Who said I was going to rely on bitcoins for my personal income?"

If you're not going to use them profitably then don't waste your time and money.  If you are going to use them profitably then that is going to wind up being a personal income yeah?  Just don't rely on them as a lifeline to keep you fed and housed.

Short and long term advise. 

Stay the hell out of those College Courses they are a waste of money, don't rely on Bitcoins for your personal income by borrowing so much money, and buy Silver instead of Gold.  As Silver corrects to its historical 1/16th ratio to Gold it will skyrocket in price.  You'll see much more gain in Silver vs. Gold.

Well the important thing to remember is that generating bitcoins will get more difficult to mine over time so mining bitcoins is only a short-term business. However, I am not sure how that will work out over the long-term especially if the price of bitcoins goes up in value year over year.

What you need to do is track all your costs like a hawk (ie. meter the electricity usage by the rig). You also need to live in a location that has cheap electricity + cold climate. So I would suggest some place where it snows. Try to go as high altitude as possible, far north or south. If possible, place your rigs outside to reduce cooling costs.

You want to run your rigs 24/7/365. Forget the college class- you won't have the time especially if your friend is going to be investing 100k.

When you generate BTC, don't just sell it ASAP on the markets, price it high so you get maximum return.

Once again, the important thing is to track your costs, including depreciation of your equipment. Saying, "I paid 7$ for electricity per bitcoin and sold the bitcoin for 8$ and made a 1$ profit" is not going to cut it.

As far as where to invest the profit from the business I'd go for physical silver/gold and stocks, primarily dividend stocks.

I know nothing of mining, but i am blessed with the ability to be allowed to communicate with the big kids so i'll post your inquiry in the mining section right now and you can check for feedback there.

edit:

here you go - http://forum.bitcoin.org/index.php?topic=15642.0