Android OS Overview Android 1.0 & Android 1.1

Android 1.0

was the first release of Android, and has an API level of 1. Since it was the first released version of Android, no platform highlights were prepared for this release.

Android 1.1 (Petit Four)

Android 1.1 has an API level of 2. Android 1.1 was known as "Petit Four" internally, though this name was not used officially.
The Android 1.1 system image delivered in the SDK is the development counterpart to the Android 1.1 production system image, deploy able to Android-powered handsets starting in February 2009.
The Android 1.1 system image delivers an updated version of the framework API. As with the Android 1.0 API, the Android 1.1 API is assigned an integer identifier — 2 — that is stored in the system itself. This identifier, called the "API Level", allows the system to correctly determine whether an application is compatible with the system, prior to installing the
application.

 The Android 1.1 system image was tested for compatibility with the Android-powered devices is T-Mobile G1

Features
•  Maps: Adds details and reviews when a user does a search on Maps and clicks on a business to view its details.
•  Dialer: In-call screen timeout default is now longer when using the speakerphone.
•  Dialer: Adds a "Show dialpad" / "Hide dialpad" item to the in-call menu, to make it easier to discover the DTMF dialpad.
•  Adds support for saving attachments from MMS
•  Adds support for marquee in layouts.

Built-in Applications

•    Alarm Clock                •    API Demos
•    Browser                       •    Calculator
•    Camera                        •    Contacts
•    Dev Tools                    •    Dialer
•    Email                           •    Maps (and Street View)
•    Messaging                   •    Music
•    Pictures                        •    Settings