dynamic sitemaps

So we have a dilemma...

We're creating an area of the site that's going to have inventory changing on a daily basis. I need to create a sitemap for this content but don't want to be dependent on SQL jobs to spit out the .xml file(s) on a schedule basis.

I'd much rather have some dynamic version of a .aspx page that would render the XML content as soon as something, like say a spider or GoogleBot, hit it. That way, it would be the most current sitemap all the time.

The question, I've posed to message boards is if Google and other engines will allow us to submit the .aspx page or point to it in our robots.txt file.

If you got any ideas, let me know. Otherwise, I'll post their response and a link to the Google message boards.

UPDATE: here's the link to the thread.