You can add a new column by clicking on gridview smarttag and add a item template something like this.
<asp:templatefield headertext="Currentdate" xmlns:asp="#unknown">
<itemtemplate>
<asp:label id="Label1" runat="server" text="<%# DateTime.Now.ToString() %>"></asp:label>
</itemtemplate>
</asp:templatefield>
Modify the date format according to your need.
Good Luck