Jamie from Trulia here; we do display open home information on the property detail page. Anyone who sends us a feed can include open home dates and times and will be automatically displayed, free of charge on the listing detail page.
What got me started thinking about this for Trulia is that we currently have 2 listings in a really nice but older private lake community with ~250 homes. Currently, there are over 20 active listings, none of which seem to be getting shown much. Price and condition are definitely not the issues in most cases. So, we recently contacted all of the listing agents in that community and proposed a neighborhood-wide open house for Sunday, Feb 3rd. Things were going great until someone had to remind me that it was Super Bowl Sunday this weekend. We moved the date out a week...
Both FMLS & MLS offer a feature to advertise open houses as does my website hosting company, Homes.com. So, why not Trulia too? C'mon Real Estate Pros - Trulia moderators are watching for your responses and inputs to this question ;-)
Jamie - Please forward me specific how-to instructions using the KWLS feed so that my "neighborhood-wide" open house can be advertised.
I can't answer for Trulia's plans, but were you here when Patrick's brilliant National Open House concept was implemented (back in November)?