There are a number of juicy web controls now available in Chameleon, one of which is the SiteUrl CSControl. As its name applies, the SiteUrl control creates a hyperlink from url information provided by the SiteUrls.config. In the .ASPX or .ASCX page its use would be something like the following where I am creating a link to my running blog at http://dbvt.com/running from my site home page.
<CSControl:SiteUrl UrlName="weblogapplication" ResourceName="weblogs"
runat="server" Parameter1="running" />
If we look at the SiteUrls.config location\url element for "weblogapplication" we see it takes an "app" (or applicationkey) parameter. The appkey of my running blog is "running," entered in the SiteUrl control's Parameter1 property. Very nice.
<url name = "weblogapplication" path="##blogdirectory##default.aspx"
pattern="##blogName##/default.aspx" physicalPath="##blogthemeDir##"
vanity="{2}?App=${{app}}" page="postlist.aspx" />