Titanium SDK's usage of require is slightly different than what NodeJS/CommonJS uses as it has an implicit base path of <project>/Resources
In Node, we'd load the core 'http' module. In Titanium we'd look for <project>/Resources/http.js. Additionally, Titanium merges the platform-specific subfolders of Resources. So...
Would look up Resources/iphone/ui/TaskWindow.js and Resources/android/ui/TaskWindow.js
Additionally you can specify a native Titanium module id to load.