In a surprise move, Apple has relented in its insistence that third-party application developers for the wildly popular iPhone sign a nondisclosure agreement before their applications can be made available for download on the iPhone App Store. The decision follows sharp criticism on developer blogs and in online technology publications from software developers who want to create applications for the iPhone. Apple dropped the NDA because it was too burdensome for developers and others, according to a statement on the company Web site.