When you write a report the item type should be available via runtime parameters (or so I was told) but it's not. When I did <<Item|itemtype>> or <<Item|itype>> I got a blank pull down.
commit message with info on this: http://git.koha-community.org/gitweb/?p=koha.git;a=commit;h=7d8b369ba4066d485e5aa7739b1b073f0db80b45
<<Pick your Item Type|itemtypes>> is the correct usage for getting the item type dropdown. :)