Since we're on the subject of the politeness of New Yorker's and the attitude that everything has its price, in New York, a simple "thank you" might be considered a costly acknowledgment.
Here's a dismal example by hacking standards, but it's still indicative of the attitude. Someone from a financial firm, known for its rating system and price indexes, had a data conversion problem. They were using Matlab--a dismal language with a bastard semantics. One of the functions they were using was Datenum(), which converts dates and times to the number of days since the year zero, in the proleptic Gregorian calendar.
The specification of this function should have been to return a floating point number equal to 1+1/86,400 (in units of days) for a date argument equal to one second after year zero. And in fact, the open source equivalent function in Octave does exactly that. However, Matlab's function differs from this in the 11th decimal place. Their technical support has been silent on the issue.
When I informed the person at the financial firm about this discrepancy, they thanked me for "my comments." In the next sentence, I was informed that that they were redoing their calculations using another method. It was stated as if the decision to do this was an entirely independent judgment, not at all informed by my observations, and completely unrelated to any problems they might have encountered using the previous method. They simply decided to change the way they were doing things, without explanation.
Finding a numerical bug that could complicate the analysis of code that depends on it is not earthshaking. But not stating what informed a decision to avoid the problem altogether is a typical New York attitude. Or perhaps the reluctance to credit others is typically corporate. Correct me if I am mistaken.
I have to agree with Paul Graham's essay on the relative lifelessness of employees: if I were an employee, I simply would have accepted the decision as a completely independent judgment, internalized it and defended it.