Apple yesterday released iPhone software version 1.1.4. The 162.1MB patch is available for download and installation through iTunes.
Some reports claim the update improves the reliability of Bluetooth, SMS and Mail on the iPhone, and that it boosts signal strength on mobile networks, but these haven't yet been confirmed. But Apple isn't making a big deal about the release, beyond letting users know it "includes bug fixes and supersedes all previous versions".
However, Apple has been expected to ship its iPhone Software Development Kit (SDK) this month, enabling a new industry creating third party applications for the iPod touch and the iPhone to emerge.
While reports have recently circulated claiming the release of the iPhone SDK may be delayed, it's also likely that the iPhone 1.1.4 updates contains functionality to support the installation of new applications.