Jon posted a module that does this.

I recently tried to use the URL rewriting module for IIS 7 to achieve the same – this rule worked for me:

<system.webServer>
  <rewrite>
    <rules>
      <rule name=“Remove .svc“>
        <match url=“^([0-9a-zA-Z-]+)/([0-9a-zA-Z-./()]*)“ />
        <action type=“Rewrite“
                url=“{R:1}.svc/{R:2}“ />
      </rule>
    </rules>
  </rewrite>
</system.webServer>

HTH