You can use multiple Leiningen profiles to accomplish what you are talking about.
(defproject project1 "0.1.0-SNAPSHOT"
:description "Something Amazing!"
:dependencies [[org.clojure/clojure "1.5.1"]]
:profiles {:v1 {:main project1.core1
:uberjar-name "uberjar1.jar"}
:v2 {:main project1.core2
:uberjar-name "uberjar2.jar"}
:v3 {:main project1.core3
:uberjar-name "uberjar3.jar"}})
And, you can build them with:
$ lein with-profile v1:v2:v3 uberjar