If whoever manages the Wiki wants to update the letter that's posted I'll send the PDF from AA.

Received 1-13-2010
"Here’s the Info You Requested on Platinum Challenges:

As discussed, we have charged your credit card and put you on a Challenge for AAdvantage Platinum membership. Here are some tips to help you succeed:

Remember that Challenges are based on points, not miles, and your goal is 10,000 points in the three-month period we discussed.
Be sure to fly AA (we know you want to anyway!) since only points earned on American Airlines, American Eagle and AmericanConnection flights (including AA codeshare flights operated by other carriers) count toward Challenges.

Select fares with high point values. If, for example, you use Deep Discount Fares, get ready to fly 20,000 miles because those fares earn points at half the rate of miles. But if you buy Discount Fares, the rate is one point per mile and you can meet your Challenge by flying 10,000 elite-qualifying miles. And if you select premium fares, you earn 1.5 points per mile and can meet the Challenge by flying just – OK, you do the math!

Know the point values you’ll earn for the booking codes you select. Yes it may look like alphabet soup, but there’s a point to these codes. In fact, there’s anywhere from 0.5 – 1.5 points!
Earn 1.5 points per mile when the purchased fare on your American Airlines ticket is booked in one of these booking codes: A F P D I J R B C Y
Earn 1.0 point per mile for these AA booking codes: H K L M V W
Earn .5 points per mile for these AA booking codes: G N Q S O (excludes tickets between North America and Latin America booked in O inventory, which are not eligible for mileage credit)

How can you determine what booking code is used for the fare you’re purchasing? Simply ask the booking agent, whether that’s your travel agent, corporate travel planner or AA Reservations representative. Or, even better, when you book your flights on AA.com, the Flight Summary screen displays the booking code in the same column as the cabin booked.

If you have the opportunity to upgrade, good for you! But with respect to the points you will earn, traveling in a premium cabin is not the same as purchasing a premium fare. When you upgrade, the points for your flights are still calculated on the fare and booking code you purchased, not the cabin that you were lucky enough to travel in!

Remember that the fee for your Challenge is nonrefundable – even if circumstances beyond your control (or ours!) prevent you from meeting the goal. But we’re thinking positive thoughts and we know you can do it!

Keep in mind that a Challenge is intended for members who are in a hurry to get to the elite level they desire and begin enjoying their benefits. Think of it as a shortcut to the status you would probably earn on your own during the normal qualification period. Assuming you’re successful, please be prepared to meet the normal criteria when it comes time to requalify for your status, since we offer only limited opportunities to earn status via a Challenge. That’s fair, right? Now you’re all set – Good Luck!"