Yes. You should take a look at Separators property.
It's a collection of separators - 1px lines that are drawn at specified times (Separator.Location) with specified colors (Separator.Color).
An example can be found in Demo/Scheduler/Default.aspx:
<DayPilot:DayPilotScheduler ID="DayPilotScheduler1" runat="server" ... >
...
<Separators>
<DayPilot:Separator Color="green" Location="02/01/2008 12:00:00" />
<DayPilot:Separator Color="green" Location="02/03/2008 12:00:00" />
<DayPilot:Separator Color="red" Location="02/02/2008 00:00:00" />
</Separators>
</DayPilot:DayPilotScheduler>