If you know the exact package name or would like detailed information, you can use the -s flag to dpkg to report the status of the package:
<pre><code>dpkg -s packagename</code></pre>
If you don't know the exact package name or would like summary information, you can use the -l flag to dpkg:
<pre><code>dpkg -l partial_packagename_with_regexs</code></pre>
partial_packagename_with_wildcards</code></pre>
--jeremy