do the captions in image gallery pro act in the same way as alt tags? (when you manually insert them using the text file handling option) do the captions carry the same seo weight as alt tags, and are the images indexed by google in the same way as images embedded on static html pages?

Are there any future seo-based developments in the works?

thanks for your help.

By default, my guess is no in the gallery but yes for the popup.  Below is the source for a page using SIG pro:

<a href="modellabs.com/joomla/media/k2/galleries/9/ABS%20prototype%201.jpg" class="sig-link" style="width:200px;height:160px;" rel="colorbox[gallery28b2e5cb19]" title="&lt;b&gt;Description&lt;/b&gt;&lt;br /&gt;You can use HTML as you can see!&lt;br /&gt;&lt;br /&gt;" target="_blank">
<img class="sig-image" src="modellabs.com/joomla/plugins/content/jw_sigpro/sigpro.transparent.gif" alt="Click to open image!" title="Click to open image!" style="width:200px;height:160px;background-image:url(modellabs.com/joomla/cache/jwsigpro_cache_2f38d2440eabs%20prototype%201.jpg);" />

<span class="sig-pseudo-caption"><b>Title</b></span>
<span class="sig-caption" title="Title">Title</span>

It appears that the gallery thumbnails seo properties are "title" and "alt".  The image in the popup uses only the "title" tag.

what is seo???????

Search Engine Optimization (SEO) is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid ("organic" or "algorithmic") search results.