The other day preparing a website to advertise a rural house in Seville, gave me to see how to insert a google calendar in which to show visitors the reservations already have the owner and so prospective tenants know that dates to perform a reservation of the house. It really is very simple. You only need to get the calendar Iframe code and insert it into the post / page you want from our wordpress. To do this, google offers the perfect tool to customize our calendar (adding and removing what interests us) you here.
If you visualize the picture above, you can see that offers great options for customizing our calendar. To only be read, and not write. We can also customize colors, size, is integrated with our gmail account, ect.
A demonstrative example of operation you have it on the web where I commented that I have made: http://casaruralloradelrio.wordpress.com/reservas-reservations/