We're always adding new features to the site, and though Ruby On Rails is a terrific framework, we use ASP.NET and the Microsoft app platform at present. We plan to add several new features to the site over the coming year, though for competitive reasons, we won't be detailing them until they hit beta, as is our policy.
Mac marketshare does continue to climb, which is great news, but it's still considerably in the single digits (e.g., this article suggests they were only seeing 3% or so of worldwide market share shipments last July, and since it has come up from many years past, they have a far smaller cumulative installed base. However, the beloved Mac does continue to climb in market share, which is great to see). Basically, while we really do love the Mac from a user standpoint, we're taking a wait-and-see approach for now, but could certainly see some dedicated development on it should the installed base share continue to climb very rapidly... but it'd need to go considerably north of where it is today.