The sudden departure of iOS Software head Scott Forstall—along with Apple's retail head John Browett—sent shockwaves through the Apple community late Monday. But it wasn't just us outsiders who were surprised by the news—engineers within Apple were also reportedly surprised by the apparent firing of such an important figure. While Apple is keeping its lips sealed over exactly what happened, details have begun to leak out about why Forstall was shown the door, painting a picture of strife among Apple's top executives.

The first is a Wall Street Journal report claiming Forstall was asked to leave because he refused to sign Apple's public apology letter for iOS 6 Maps in September. Forstall reportedly felt an apology wasn't necessary and chose not to participate in the decision to acknowledge Maps' problems to the public, leaving Apple CEO Tim Cook to sign his own name to the letter. Forstall, known by many to have a "strong-headed" personality, also reportedly told people that there was no "decider" within Apple after Steve Jobs' death. Sources claim he sent an e-mail to the iOS team in order to chide them for not coming up with big enough ideas.

Other reports touch on "tensions" between Forstall and other Apple executives. The New York Times mentioned that Forstall had been clashing with other executives "for some time" before the Maps apology letter—specifically, he had clashed heavily with Apple's head designer Jonathan Ive. "[T]he relationship between Mr. Forstall and Mr. Ive had soured to a point that the two executives would not sit in the same meeting room together," the Times wrote.

This report was echoed by CNN's Fortune: "It is being said that Forstall didn't get along with Jony Ive. The knighted designer won that battle." As pointed out by John Gruber, this was foreshadowed by an interview with Ive earlier this year, wherein Ive "winced" when asked about the stitched leather interface on some iOS and OS X applications. At the time, Ive gave a statement saying, "In terms of those elements you're talking about, I'm not really connected to that."

But Forstall's clashes went beyond Ive, too. "A senior Apple employee who asked not to be named said Mr. Forstall had also incurred the ire of other executives after inserting himself into product development that went beyond his role at the company," the Times said. "One person in touch with Apple executives said the mood of people at the company was largely positive about Mr. Forstall’s departure."

This is a sentiment echoed by our own sources, who had unpublishable things to say about Forstall—they generally seemed relieved at the news. The same with GigaOm: "Forstall’s firing was met with a sense of quiet jubilation, especially among people who worked in the engineering groups. Or as one of my sources quipped: there are a lot of people going for celebratory drinks, even if there is a little bit of doubt about their roles in the future."

GigaOm offers a few more details as well, including the fact that engineering teams seemed to be "caught off guard" by the Forstall announcement. This is in contrast with engineering head Bob Mansfield's retirement in June (which has since been tweaked slightly to allow him to stay on board)—Mansfield's resignation was reportedly "masterfully planned," while Forstall's departure was swiftly executed.

As for Browett, his not-even-a-year stint at Apple has come to a less surprising end. We'll have more on what went wrong with Browett, but the general public reaction to his firing has been more muted.

Update: Chris Foresman's post on Browett's 7-month tenure is now up.