Hey Roger,

Here is a utility method that gets the current portal's login URL.

Public Shared Function GetLoginUrl(ByVal portalSettings As PortalSettings, ByVal request As HttpRequest) As String

    If ((portalSettings Is Nothing) OrElse (request Is Nothing)) Then

        Throw New ArgumentNullException(IIf((portalSettings Is Nothing), "portalSettings", "request"))

    End If

    Dim tabID As Integer = portalSettings.ActiveTab.TabID

    Dim controlKey As String = "Login"

    Dim rawUrl As String = request.RawUrl

    If (rawUrl.IndexOf("?returnurl=", StringComparison.OrdinalIgnoreCase) > -1) Then

        rawUrl = rawUrl.Substring(0, rawUrl.IndexOf("?returnurl=", StringComparison.OrdinalIgnoreCase))

    End If

    rawUrl = HttpUtility.UrlEncode(rawUrl)

    If (Not Null.IsNull(portalSettings.LoginTabId) AndAlso String.IsNullOrEmpty(request.QueryString.Item("override"))) Then

        controlKey = String.Empty

        tabID = portalSettings.LoginTabId

    ElseIf Not Null.IsNull(portalSettings.HomeTabId) Then

        tabID = portalSettings.HomeTabId

    End If

    Return Globals.NavigateURL(tabID, controlKey, New String() { ("returnUrl=" & rawUrl) })

End Function

http://stackoverflow.com/questions/1246570/how-do-i-get-the-portals-current-login-url-in-dotnetnuke

Hope that helps,

Ian