Subtext 1.9.4 is available for download from sourceforge. Steve has the breakdown of what's changed; for me the important fixes include

New features include

If you're upgrading you should note that Google SiteMap support does need a change to your existing web.config file. In the HttpHandlers section you need to add

<HttpHandler 
pattern="(?:/Sitemap/?(Sitemap\.ashx)?)$"
type="Subtext.Web.SiteMap.SiteMapHttpHandler
Subtext.Web"
handlerType="Direct"/>

Your sitemap URL will be ~/sitemap/sitemap.ashx 

Those of you using Google SiteMaps already may know that google wants the sitemap as high up the directory structure as possible and asks you to register the /sitemap directory as a seperate web site. If you don't want to jump through that hoop you can change the pattern for the handler to be

<HttpHandler 
pattern="(?:/Sitemap\.ashx)$"
type="Subtext.Web.SiteMap.SiteMapHttpHandler
Subtext.Web"
handlerType="Direct"/>

to have the sitemap appear in ~/sitemap.ashx