diff --git a/Control/Monad/Omega.hs b/Control/Monad/Omega.hs
--- a/Control/Monad/Omega.hs
+++ b/Control/Monad/Omega.hs
@@ -27,6 +27,11 @@
 --
 -- This monad gets its name because it is a monad over sets of order type
 -- omega.
+--
+-- Warning: Omega is only a monad when the results of @runOmega@ are
+-- interpreted as a set; that is, a valid transformation according to the
+-- monad laws may change the order of the results.  However, the same
+-- set of results will always be reachable. 
 ----------------------------------------------
 
 module Control.Monad.Omega 
@@ -66,6 +71,10 @@
     return x = Omega [x]
     Omega m >>= f = Omega $ diagonal $ map (runOmega . f) m
     fail _ = Omega []
+
+instance Monad.MonadPlus Omega where
+    mzero = Omega []
+    mplus (Omega xs) (Omega ys) = Omega (diagonal [xs,ys])
 
 instance Applicative.Applicative Omega where
     pure = return
diff --git a/control-monad-omega.cabal b/control-monad-omega.cabal
--- a/control-monad-omega.cabal
+++ b/control-monad-omega.cabal
@@ -2,11 +2,12 @@
 Description:
     A monad for enumerating sets: like the list
     monad but breadth-first.
-Version: 0.2
+Version: 0.3
 Stability: experimental
 Synopsis: A breadth-first list monad.
 License: PublicDomain
 Category: Control
+Homepage: http://github.com/luqui/control-monad-omega
 Author: Luke Palmer
 Maintainer: lrpalmer@gmail.com
 Build-Type: Simple