Hell hath no fury like a US. Chamber of Commerce spurned. Perhaps that explains the business trade association’s response to Apple’s very public resignation of its membership in the group this week.

You may recall that Apple on Monday quit the US Chamber of Commerce, citing differences of opinion with the group’s stance on climate change. In a letter to Chamber President Thomas J. Donohue, Apple’s Catherine A. Novelli specifically contrasted the group’s opposition to a carbon emissions bill working its way through Congress with Apple’s stepped up environmental efforts, adding, “it is frustrating to find the Chamber at odds with us in this effort.”

Well, two can play the letter-writing game. So Donohue sat down in front of a keyboard this week and pounded out a response which, as this Wall Street Journal report suggests, does not exactly strike a conciliatory tone. Donohue wrote:

It is unfortunate that your company didn’t take the time to understand the Chamber’s position on climate and forfeited the opportunity to advance a 21st century approach to climate change.

That approach, incidentally, will not be the current proposal in Congress, which Donohue said “will cause Americans to lose their jobs and shift greenhouse gas emissions overseas, negating potential climate benefits,” according to the Journal. That’s not a stance likely to give Cupertino any second thoughts about the decision to drop out of the Chamber of Commerce.

Why is Apple’s departure from the trade association drawing this level of attention? After all, the Chamber of Commerce still claims to represent 3 million businesses, even after Apple and a handful of other companies have ankled the group. BusinessWeek’s Adam Aston tackles that question in his Green Business blog, pointing to both Apple’s high profile and the “starkness of its statement” in resigning from the trade group. NPR also takes a closer look at the story, pointing to the resignations of Apple, PG&E, Exelon, and PNM Resources as a sign that on the tricky issue of global warming, the business community doesn’t exactly speak with a single voice.