Our little blue and green TUAW tipster birdie is chirpin' again, and this time the news could make both developers and consumers happy if everything pans out. From what we hear, evidence has been found that references to the ARM architecture appear in several of Leopard's standard include files, such as those found in the /usr/include/machine directory. Since ARM is the type of processor found in the iPhone but not in any Macs (for the most part, virtually any Mac still in service is likely running on PowerPC or the newer Intel processors), this is leading some to believe that these references are a sign that Leopard could usher in an update to Apple's Xcode development app, allowing Mac OS X developers access to the current holy grail of making true apps for the iPhone - apps that would be able to take advantage of things like synching data, storing files, RSS feeds and a whole lot more. Imagine being able to truly travel with, edit and create new Yojimbo notes (instead of simply view them with Webjimbo), bring your NetNewsWire feeds or do basic blogging with a mini-MarsEdit or ecto, and you have only seen the tip of the iceberg that is the iPhone's 3rd party app potential.
[Update: Adrian, Webjimbo's developer, set me straight in the comments that Webjimbo can in fact create and edit Yojimbo notes, bookmarks, archives and serials. This leads me to agree with Derik DeLong at MacUser: Webjimbo is indeed one of, if not the, coolest implementations of web 2.0 technology that integrates with a desktop app.]
Of course, for now this is merely speculation, but it's still speculation based on evidence whose existence is a bit puzzling. Fortunately, October is getting closer by the day, so we should have a clearer idea as to when a true iPhone SDK is coming. I simply hope that it's still a closely guarded question of when in Apple's eyes, instead of 'if.'