diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2012, Brent Yorgey
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Brent Yorgey nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/highlight-versions.cabal b/highlight-versions.cabal
new file mode 100644
--- /dev/null
+++ b/highlight-versions.cabal
@@ -0,0 +1,41 @@
+name:                highlight-versions
+version:             0.1.0.0
+synopsis:            Highlight package versions which differ from the latest
+                     version on Hackage
+description:         This package provides an executable which reads from
+                     stdin and outputs the same thing to stdout,
+                     except that any lines which look like package
+                     identifiers (e.g. foo-0.3.2) are highlighted if
+                     the version does not match the latest version on
+                     Hackage: red if the version is less than the
+                     version on Hackage, or cyan if greater.  In
+                     addition, the Hackage version is shown in blue.
+                     .
+                     In particular, it can be useful to pipe the
+                     output of @cabal(-dev) install --dry-run@ through
+                     this program, to aid in checking the install
+                     plan. It's usually a good idea to understand why
+                     an outdated package is being installed; otherwise
+                     it can indicate that something needs to be updated.
+license:             BSD3
+license-file:        LICENSE
+author:              Brent Yorgey
+maintainer:          byorgey@cis.upenn.edu
+copyright:           Copyright 2012 Brent Yorgey
+category:            Distribution
+build-type:          Simple
+cabal-version:       >=1.10
+
+source-repository head
+  type: darcs
+  location: http://code.haskell.org/~byorgey/code/highlight-versions
+
+executable highlight-versions
+  main-is:             Highlight.hs
+  build-depends:       base >= 4 && < 5,
+                       containers >= 0.4 && < 0.6,
+                       hackage-db ==1.3.*,
+                       Cabal ==1.14.*,
+                       ansi-terminal ==0.5.*
+  hs-source-dirs:      src
+  default-language:    Haskell2010
diff --git a/src/Highlight.hs b/src/Highlight.hs
new file mode 100644
--- /dev/null
+++ b/src/Highlight.hs
@@ -0,0 +1,53 @@
+module Main where
+
+import qualified Data.Map as M
+import           Distribution.Hackage.DB
+import           Distribution.Text (simpleParse)
+import           Prelude
+import qualified Prelude as P (map)
+import           System.Console.ANSI
+
+main = do
+  db <- readHackage
+  input <- getContents
+  let ls = lines input
+  mapM_ (highlightOutdated db) ls
+
+-- | Take an individual line of output and see if it looks like a
+--   package identifier (/i.e./ @foo-0.3.2@).  If so, compare it to
+--   the latest version on Hackage, and highlight it if the version
+--   differs (in red if the version is older than the latest on
+--   Hackage, or cyan if newer), also printing the version of the
+--   latest Hackage release in blue.
+highlightOutdated :: Hackage -> String -> IO ()
+highlightOutdated db s =
+  -- try to parse this line as a package identifier (like foo-1.3.2)
+  case simpleParse s of
+    Nothing    -> putStrLn s
+    Just pkgId ->
+      -- look up this package name in the Hackage DB
+      case (M.lookup (getPkgName pkgId) db) of
+        Nothing -> putStrLn s
+        Just versions -> do
+          -- get the latest version and compare it to the stated version
+          let latest    = maximum . P.map fst . M.assocs $ versions
+          case compare (pkgVersion pkgId) latest of
+            EQ -> putStrLn s
+            LT -> doHighlight s latest Red    -- show outdated versions in red
+            GT -> doHighlight s latest Cyan   -- show newer versions in cyan
+
+-- | Output a package name highlighted in a given color, along with
+--   another version in blue.
+doHighlight :: String -> Version -> Color -> IO ()
+doHighlight s latest color = do
+  setSGR [SetColor Foreground Vivid color]
+  putStr s
+  setSGR []
+  putStr " ("
+  setSGR [SetColor Foreground Vivid Blue]
+  putStr (showVersion latest)
+  setSGR []
+  putStrLn ")"
+
+getPkgName :: PackageIdentifier -> String
+getPkgName pkgId = case pkgName pkgId of PackageName name -> name