From Eric Lippert, a Senior Software Design Engineer on the C# team:
Why was the var keyword introduced?
There are two reasons, one which
exists today, one which will crop up
in 3.0.
The first reason is that this code is
incredibly ugly because of all the
redundancy:
Dictionary> mylists = new Dictionary>();
And that's a simple example – I've
written worse. Any time you're forced
to type exactly the same thing twice,
that's a redundancy that we can
remove. Much nicer to write
var mylists = new Dictionary>();
and let the compiler figure out what
the type is based on the assignment.
Second, C# 3.0 introduces anonymous
types. Since anonymous types by
definition have no names, you need to
be able to infer the type of the
variable from the initializing
expression if its type is anonymous.
Emphasis mine. The whole article, C# 3.0 is still statically typed, honest!, and the ensuing series are pretty good.
This is what var is for. Other uses probably will not work so well. Any comparison to JScript, VBScript, or dynamic typing is total bunk. Note again, var is required in order to have certain other features work in .NET.
