It's a matter of taste. All this fussing about the type of a variable disappears when you get used to dynamically typed languages. That is, if you ever start to like them (I'm not sure if everybody can, but I do).
C#'s var is pretty cool in that it looks like dynamic typing, but actually is static typing - the compiler enforces correct usage.
The type of your variable is not really that important (this has been said before). It should be relatively clear from the context (its interactions with other variables and methods) and its name - don't expect customerList to contain an int...
I am still waiting to see what my boss thinks of this matter - I got a blanket "go ahead" to use any new constructs in 3.5, but what will we do about maintenance?
