Alright folks. I am going to make the disclaimer that I have not programmed in Java in over 10 years and html so this took me a long time and I am sure I am far from a completed solution. I am hoping that others can quickly work off of the solution I am starting here or that this inspires you to help me complete this. I have run out of time today, but here is what I have so far. I went to the open source Google Code Project Slideshow website today.
http://code.google.com/p/slideshow/ and downloaded the source files. Unzip the directory to c:\subsonic\jetty\2132\webapp. You should now have the following folders and files, CSS, images, js, index.html, and readme in addition to the files that were already there. You will want to change the index.html file you just downloaded to something else. I changed it to pictures.html. At this point you should be able to point your subsonic url to xyz.subsonic.org/pictures.html and see a working version of the slideshow with the examples given. If you navigate to c:\subsonic\jetty\2132\webapp\WEB-INF\jsp you will find the top.jsp file. Open it in your editor of choice (notepad). This will allow you to add an extra button at the top of your subsonic page. I added the line <fmt:message key="top.pictures" var="pictures"/> just below the same line with podcast in it. Then I copied and added
<td style="min-width:4em;padding-right:1.5em">
<a href="pictures.html" target="main"><img src="<spring:theme code="homeImage"/>" title="${pictures}" alt="${pictures}"></a><br>
<a href="pictures.html" target="main">${home}</a>
</td>
just below the matching line with home.view in it. Click save.
If you refresh your subsonic home page, you will see two "home" icons at the top. If you select the second one, you should see where the slideshow player has now been embedded into the interface.
I am not fast enough or good enough with java to incorporate this with a pictures folder like the movie or music folders we all currently have. Also, I cannot figure out how to make this interface more secure like with the movies or the music. I am hoping this is a good enough start to help others take it from here and easily incorporate it into the interface.