I started looking at writing some Jscript today.
I have got my head around the new webresource setting and where you have to load the jscript file.
I was then trying to work out the best way to write jscript code and what environment.
The best free solution seems to be Visual Studio. but I also found this excellent post which gives you some intellisense for CRM 2011
http://www.patrickverbeeten.com/pages/ContentItemPage.aspx?id=9&item=118&p=true
What Patrick has done is basically build in intellisense for the Xrm.page new functionality in CRM 2011.
Anything that makes Jscript development easier is ok with me. I have been looking at some other tools which hopefully will add intellisense to the different entities.
I haven’t got it to work yet but when I do I shall post a link for it.