There's now a Google Group for discussion and questions.

Here's a brief tutorial that covers some Seesaw basics. It assumes no knowledge of Swing or Java.

Here's the slides from a Clojure/West 2012 talk on the Seesaw. Best viewed in Chrome or Safari.

Seesaw: Clojure + UI

See the Seesaw Wiki and the Seesaw API Docs for more detailed docs. Note that the docs in the code (use the doc function!) are always the most up-to-date and trustworthy.

Seesaw is a library/DSL for constructing user interfaces in Clojure. It happens to be built on Swing, but please don't hold that against it.

Features

Seesaw is compatible with both Clojure 1.4, but will probably work fine with 1.3 and 1.5. Maybe even 1.2.

Swing knowledge is not required for many apps!
Construct widgets with simple functions, e.g. (listbox :model (range 100))
Support for all of Swing's built-in widgets as well as SwingX.
Support for all of Swing's layout managers as well as MigLayout, and JGoodies Forms
Convenient shortcuts for most properties. For example, :background :blue or :background "#00f", or :size [640 :by 480].
CSS-style selectors with same syntax as Enlive.
Unified, extensible event API
Unified, extensible selection API
Widget binding, i.e. map changes from one widget into one or more others in a more functional style. Also integrates with Clojure's reference types.
Graphics
i18n
An extensive test suite

There are numerous Seesaw examples in test/seesaw/test/examples.

TL;DR

Here's how you use Seesaw with Leiningen

Install lein as described and then:

$ lein new hello-seesaw
$ cd hello-seesaw

Add Seesaw to project.clj

(defproject hello-seesaw "1.0.0-SNAPSHOT"
  :description "FIXME: write"
  :dependencies [[org.clojure/clojure "1.4.0"]
                [seesaw "x.y.z"]])

Replace the Seesaw version with whatever the latest version tag is. See below!

Now edit the generated src/hello_seesaw/core.clj file:

(ns hello-seesaw.core
  (:use seesaw.core))

(defn -main [& args]
  (invoke-later
    (-> (frame :title "Hello",
           :content "Hello, Seesaw",
           :on-close :exit)
     pack!
     show!)))

Now run it:

$ lein run -m hello-seesaw.core

NOTE: Here's how you can run against the bleeding edge of Seesaw:

Clone Seesaw from github. Fork if you like. Switch to the "develop" branch.
In your Seesaw checkout, run lein install to build it. Note that Seesaw uses Leiningen 2 as of 3 NOV 2012!
In your project's project.clj file, change the Seesaw version to X.Y.Z-SNAPSHOT to match whatever's in Seesaw's project.clj.
Run lein deps ... actually you can just start coding. lein deps is almost never necessary.
Move along