"What about the Linux-based open source Android platform that runs underneath all of the consumer-level apps and features? The easiest way to get a feel for Android as a platform is to explore what developers are doing with it. The G1 includes an over-the-air application catalog and installer tied to the Android Market, through which you can browse hundreds of Android apps and read the reviews of other users.
"So far, all of the apps in Android Market are free of charge, which cannot be said of the other two officially sanctioned Android app portals run by longtime mobile app vendors Handango and MobiHand. Selections include the usual bevy of single-purpose IM clients and Web app front ends from sites you've never heard of -- but they also include some interesting utilities that actually try to add functionality to the phone.
"Several apps tweak the behavior of built-in apps, such as by adding to the default email client. Others are attempts to add useful apps such as barcode scanning and text editing that are commonplace on other mobile phone platforms. One of my personal favorites is G1 Central, which alters your outgoing Caller ID to reflect your GrandCentral phone number -- functionality not provided on the G1 even though GrandCentral is a Google service."
