This document discusses several popular MVVM frameworks for building cross-platform applications with XAML and .NET/C#, including MVVM Light, Caliburn.Micro, Simple MVVM, ReactiveUI, Catel, and MvvmCross. It provides an overview of key features of each framework such as base view models, command implementations, messaging, navigation, data binding, and cross-platform support. Popular features include shared view models across platforms, model-view-viewmodel patterns, messaging support, and plugins for platform-specific functionality.