One improvement in ASP.NET 2.0 regarding Server.Transfer is a new property on the Page called PreviousPage that basically provides a reference to the source page.  When a cross page request occurs, the PreviousPage property of the current Page class holds a reference to the page that caused the postback.  If the page is not the target of a cross-page posting or if the pages are in different applications, the PreviousPage property is not initialized.  After cross-posts back from source page to the target page, the target page accesses information on the source page.  Note that cross page posting is basically a client side transfer.