Release Phobia
I have seen too many mobile projects fail because they run out of money due to what I call ‘release phobia’ - the inability to release a completed application and instead continually re-engineer it to make it better.
Release phobia usually, but not always, occurs on the server as opposed to phone side. Toward the end of development, someone gets a bright idea (or more usually many bright ideas) that they think will their users will love. However, they are usually wrong and the extra development jeopardises the project in terms of time and cost.
My advice is don’t spend months building features users may not like and may never actually use. Instead, learn from what users actually do. Decide on what you will do, build it, release it, get some feedback and then iterate.
UPDATE: Andyeb on twitter made the observation that release phobia is exacerbated on iPhone because "developers are worried about not being able to fix a botched release quickly"