Cms page (or static block) inside product description

From any CMS field in Magento you should be able to refer to a static block - you can even refer to it programmatically:

Adding Static and non-static blocks directly to templates:

<?php echo $this->getLayout()
->createBlock('cms/block')
->setBlockId('your_block_id')->toHtml(); ?> 

Short code inside another block or cms page :

{{block type="cms/block" block_id="your_block_id"}}

Some more reading:

http://bradfrostweb.com/blog/web/magento-static-blocks/

_{Source: https://stackoverflow.com/questions/8007555/how-to-add-a-cms-static-block-to-all-pages-in-magento}

Although I don't recommend it because this may lead to performance issues (more time needed for processing the product description), I wrote a tutorial on how to do this. You can find it here.
It worked for me for products and categories without a problem.
The main idea is to process the product description (or any other attribute) just like the content of a CMS page or a CMS block is processed before returning the content. I mean It should be able to support directives like {{block type="..."}}, {{store url=""}}, {{skin}} and others.