Not sure if you still are looking for info, but I ended up using jquery to create a splash page – how you go about it really depends on whether you want the splash to appear with every return to “home” or the front_page() or not.
If yes, you can create divs that are display:none to start with, then use the fairly simple jquery functions to show/hide or fadeIn/fadeOut content in them.
If not, create a new static page with your splash, set it to be the “home” or front_page() using settings.
An example can be seen at fixeselfcenter.com
This uses a static WordPress Page set to be “home” in the settings and then the link “Home” goes to what had been the front_page in the past by referencing its permalink.
That link “Home” uses conditional logic if (is_page(3)) {} else {echo //code to write the link}
to either write the link or not based on whether you are on the perceived home page (page 3) or not.
Previously, it had used the (if (is_front_page()) conditional to show that link (since it WAS the front page in the past).
WordPress is cool – a truly easy to use CMS besides the basic blogging stuff.