One of the things that will be apparent to anyone who digs into CRM 2011 form customization is that it is quite a bit different than Dynamics CRM 4.  One of the fundamental differences is the approach to form scripting.  In CRM 4, each entity form has a set of events that you can script using jscript, including on change of the form, on load of the form, and on save of the form.  This is great functionality, but in CRM 4, it was somewhat difficult to manage the jscript, because you wound up with multiple copies of the same functions on various entities. This made updating these functions problematic, because there was no central jscript library.

CRM 2011 changes this in a big way, by introducing support for common jscript libraries that can be called from any entity.  This makes it easier to upgrade your jscript functions and manage them like any other code.

This is great change, and also probably one that may be a bit of a learning curve for long time Dynamics CRM customizers.

My MVP friend Ayaz Ahmad has recently posted a detailed look at how to use jscript libraries in CRM 2011, with screenshots.

In Microsoft Dynamics CRM 4, it is a very tedious task for system customizers to manage and track JavaScript. System Customizers/Developers have to write JavaScript on every event handler on the form. But Microsoft Dynamics CRM 2011 provides JavaScript libraries that can be utilized on events and forms across the solution. Now common JavaScript functions can be written at one centralized JavaScript file and utilized across solution.

Moreover, multiple JavaScript libraries can be created. For example, one common library for general CRM Service calls and one common library for UI manipulation and so on.

Read the rest of the post at Ayaz' blog.  He's definitely a "must follow" on Twitter too!