Hopefully the following info will help someone else.  I was finally able to determine why I couldn't set the SelectedIndex on pageload.  It's definitely a Infragistics bug, but at least I figure it out and found a way around it.

The Problem… a review

On each of the tabs I had there was a just a listview control, whenever I tried to specify the tab it would say it couldn't find this control "IPageableItemContainer 'listview' not found"  and the page would bomb.  

Work Around … the real problem

I figured out it wasn't the listview, it was the datapager above the listview.  The datapager refers to the listview, but apparently something it not loading properly when I set the selectedindex server side.  If I remove the pager or move the pager to be only under the listview the selectedindex setting works.  Its not a perfect fix since I always have my paging at the top and bottom of listviews but at least there is a work around. 

Hopefully someone from Infragistics can reproduce this problem now that I have more info and can fix it. 

<asp:DataPager ID="datapageernamehere" runat="server" PagedControlID="listviewnamehere" PageSize="20">
           <Fields>
            <asp:NumericPagerField ButtonType="Link" />
           </Fields>
          </asp:DataPager>  

Moved the logic to Page_Load but getting the same error.

 

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

  If Not Page.IsPostBack Then
   'First Load
   If Not Request.Item("t") Is Nothing Then
    If IsNumeric(Request.Item("t")) Then
     WebTab1.SelectedIndex = CInt(Request.Item("t"))
    End If
   Else
    WebTab1.SelectedIndex = 0
   End If

  Else
   'Post Back

  End If

 End Sub

  <asp:ScriptManager ID="ScriptManager1" runat="server">
  </asp:ScriptManager>
  <asp:UpdatePanel ID="UpdatePanel1" runat="server">
   <ContentTemplate>
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
    <ig:WebTab ID="WebTab1" runat="server" Height="184px" Width="700px" StyleSetName="Default"
     EnableOverlappingTabs="true">
     <Tabs>
      <ig:ContentTabItem runat="server" Text="tab 1">
      </ig:ContentTabItem>
      <ig:ContentTabItem runat="server" Text="tab 2">
      </ig:ContentTabItem>
      <ig:ContentTabItem runat="server" Text="tab 3">
      </ig:ContentTabItem>
     </Tabs>
     <PostBackOptions EnableAjax="true" EnableLoadOnDemand="true" />
    </ig:WebTab>
   </ContentTemplate>
  </asp:UpdatePanel>

 Protected Sub WebTab1_SelectedIndexChanged(ByVal sender As Object, ByVal e As Infragistics.Web.UI.LayoutControls.TabSelectedIndexChangedEventArgs) Handles WebTab1.SelectedIndexChanged
  Label1.Text = Now.ToLongTimeString
 End Sub

The SelectedIndexChanged event only first for the first click on each tab, have tried a number of combinations with PostBackOptions with no luck.

Already have the webtab control in an update panel.  Trying to get it to fire on every tab change, not just the first click.