PhoneGap is a free open-source plugin for Eclipse that lets you write Android and iPhone apps in html/javascript (it even has jQuery-like UI plugins). As of version 0.9.1 it’s still very rough and it was a real pain to install and compile projects. Hopefully you won’t have to go through the same pain I did, so I updated the phonegap getting-started wiki with these notes:

Make sure android sdk and ant are not installed in directories that have a space in the name (i.e. do not install in c:\Program Files).

After installing java jdk (NOT the jre), eclipse, android sdk (following all their directions and getting a helloworld app working), rubyinstall, ant, and phonegap, make sure you have these environment variables set up:
WINDOWS: (Right-click My Computer (or Computer), Properties, Advanced tab, Environment Variables button)
• ANDROID_HOME (for example: C:/android-sdk-windows)
• ANT_HOME (for example: C:\apache-ant-1.8.1)
• JAVA_HOME (for example: C:\Program Files\Java\jdk1.6.0_20)
• Path = (includes these) (for example: C:\Ruby191\bin; C:\apache-ant-1.8.1\bin; C:\Program Files\Java\jdk1.6.0_20\bin; C:\android-sdk-windows\tools)

Once you have all that set up, you’ll start to have meaningful errors when you try to build the example phonegap project.

Random notes:
• The droidgap script in your phonegap folder is set to target_id 8, but you need to run “android.bat list targets” from your phonegap folder to get your list of target_ids for each platform you have installed. For example if I only have 1.6 and 2.2, then the target_id in the droidgap script for 1.6 would be set to “1” and 2.2 would be “2”.
• In the build command, the package name can not be just the app name, you’ll need to add “com.” or something to make the phonegap compiler happy (i.e. “example” “com.example”).