One of the things we stress in the Blogosopher course is adherence to W3C standards- and especially, accessibility for the blind. The main reason is that search engines act just like blind people on the web- they can’ t go where they don’t know where they are going.
Part of web standards is using code that everyone understands- not any proprietary systems- like the one Rappattoni uses to build their Multiple Listing Service (MLS) sites.
Apparently they require Microsoft Internet Explorer to work with their site- and Microsoft abandoned the program for the Apple Macintosh in January of 2006- mostly because they were having a hard enough time updating Explorer for the PC (which is still not RSS aware).
I found the link above – with instructions for installing some software for a Mac so you can view their site. But, this is a reminder to companies that decide to build sites based on proprietary standards or software technology- you may be shutting out some of your best customers without knowing it.