I just installed v 1.4 of the Great Real Estate plugin into an existing WP 3.2.1 environment, and had only minor issues, all related to compatibility with the theme I was using. The implementation instructions did not work with my theme (RT Affinity) because the theme's default page template was very complex, and did not match what Great Real Estate assumed a basic page template should contain. I got around this with a variation of the author's provided instructions for customizing the plugin's page templates.
Basically I had to edit the sample listings.php and listingpage.php templates provided by the plugin author to strip out anything that a theme's normal page template code would and should do for itself, like invoking headers, footers and sidebars, typical WP links, etc, and also removing the page template ID code at the top so WP would no longer think they were page templates. This left only the GRE specific code. Then I saved the edited sample templates in my theme's main folder with special names (simply putting underscore at the front of the applicable file names).
The second step was to "clone" two copies of my theme's default page template (usually page.php), rename one of them to listings.php and the other to listingpage.php, change the template IDs at the top of the template file to match what I stripped out of the corresponding sample files, and inserted code to include the applicable modified GRE sample code file immediately after the theme's normal code displays the actual page content and just before the code for the "Edit this Entry" link. I can't tell you where that point might be for your theme's page template, as they will all be different.
The new include code added to the cloned and modified listings.php file, just after displaying normal page content, looked like this:
<div class="entry-content"> <?php if(file_exists(dirname(__FILE__) . '/_listings.php')) include (dirname(__FILE__) . '/_listings.php'); ?> </div>
All this was emailed to the author, so future users may see it in an updated version of the implementation instructions at some point.