I totally thought I'd get yelled at for being off topic and pretentiousness, but yeah.. I'm also fascinated by language.
I know Wikipedia isn't the most credible source, but the citations on the "learning curve" page looked pretty legit. One source that particularly stood out was:
7. Laparoscopic Colon Resection Early in the Learning Curve", Ann Surg. 2006 June; 243(6): 730–737, see the "Discussions" section, Dr. Smith's remark about the usage of the term "steep learning curve":
"First, semantics. A steep learning curve is one where you gain proficiency over a short number of trials. That means the curve is steep. I think semantically we are really talking about a prolonged or long learning curve. I know it is a subtle distinction, but I can't miss the opportunity to make that point."
http://en.wikipedia.org/wiki/Learning_curve
