<p>When I started programming I was using Ruby and the colorful little notepad that came with it. Since I started learning Java I've been using Eclipse, which is apparently an IDE. Now I've read a bit about this Mono on Reddit, but I don't think I understand exactly what it is. The website says it is a development framework: is that just another word for IDE? I'm a true beginner who wants to work in a number of languages, from Java and Ruby to z80 and ARM9... is there an IDE or development framework that might be best for little me?</p>

a framework is a set of classes and supporting code to be used to build applications. this can be as simple as the C standard library or as complex as the Smalltalk environment, or may even include the infrastructure for complex application like Dynamic or ERP systems - but essentially a framework is just a class library
an IDE (Integrated Development Environment) is a tool for writing programs; this tool is essentially a just a program that contains a text-editor that supports compilation and debugging et al
[mono is a linux-based implementation of the .NET framework, by the way]