Local macros and symbol macros

Local macros are defined by a macrolet form. They are usable only
inside its body. Symbol macros can be defined globally
(defsymbolmacro) or locally (symbol-macrolet). A symbol
macro defines a form that replaces a symbol during macro
expansion. Function arguments and symbols bound in let
forms are not subject to symbol macro expansion.

Local macros are most useful in the definition of the expansion
of another macro, they may be used anywhere. Global symbol
macros can be used only inside a with-symbol-macros form.

Vars in clojure.contrib.macro-utils