Is it possible to open a response.redirect in a new window?

Protected Sub btnPrintablePage_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnPrintablePage.Click
        Response.Redirect("../PrintablePages/sqlPrint.aspx?ClientID={0}")
End Sub

no.

The redirect is a response that is always sent back from the server to the window making the request.

opening a new window is something that must be initiated at the client.

Response.Redirect run on the server you have to use client script to open the window

you can use JavaScript window.Open() 

window.open('page.html', "_blank");

or from server side  

response.write("<script>");
response.write("window.open('page.html','_blank')");
response.write("</script>");

Here's a cool function that does this.

http://weblogs.asp.net/infinitiesloop/archive/2007/09/25/response-redirect-into-a-new-window-with-extension-methods.aspx

 Wow thanks Partha... great job