It is now possible to embed any 3d model on Google's 3d Wharehouse on a web page.
Here is my Spiral Stair Dynamic Component Demo. It is a try at making the handrail completely dynamic. This demo is close, but not quite there yet. And below that, the options dialog for all the stair settings.
To include a model in your web page, first visit the 3d Warehouse page for that model. Then near the bottom, click the Include link, and select the 3d Option. Copy and paste the code into your web page.