We mentioned in passing during our pre-iPhone 3.0 rumor round-up that:

G-Maps has mysteriously disappeared from the App Store, and will “return soon”…

While XRoad's website said the US East and West coast maps were being improved, the real reason speculated at the time is that they were perhaps about to re-appear as a full turn-by-turn navigation solution as part of the Premium App Store. Neither of those things happened, and now Gizmodo shares what might really have been going on:

Update: Some developers have told us that the reason G-Map has been pulled is that by including turn-by-turn navigation, it violated the terms of agreement—which is why it was the first turn-by-turn app to come out.

Of course, the App Store terms of service have now changed, allowing for turn-by-turn as long as the developer "brings their own maps" so we'll have to keep an eye on this one and see what happens come "summer" and the official iPhone 3.0 release...