http://bp0.blogger.com/_86aUuFWLIEw/Rp-jbWqasMI/AAAAAAAAALM/EJf3koDls6M/s400/gbase_main_ingredient.jpg

We can see how Google use a mix of html elements to expand classic HTML Select

First viewed at Google Base
http://base.google.com/base/s2?q=paella&btnG=Search+Base&a_n0=recipes&a_y0=9&nd=1&showrefine=1&hl=en&gl=US

I'm sure Google will increase the use of these advanced selects along their services

They've been doing this for a long time in Google Base.