Yesterday, we mentioned that Apple’s newest beta of its iPhone OS 4.0 operating system included reference to tethering via AT&T. The cool cats at Gizmodo have apparently located a custom dictionary that will allow users to add their own words and unique spellings, and will automatically recommend those words as users type them.

The new option, “Edit User Dictionary,” can be found in the Keyboard section of the handsets Settings application in beta 4 of iPhone OS 4.0. There, users can press the plus button and add their own words.

This will allow users to bypass the “learning” feature found in previous versions of the iPhone OS, where the software will remember when the user chooses to discard a recommended spelling from the built-in dictionary.

Stay tuned for additional details as they become available.