The SpreadsheetGear WorkbookView control (our main UI control) is designed for the Windows Forms framework. We do have customers who claim to be using it from their WPF applications by using some sort of wrapper around the control. We do not do any testing in this framework and do not have any information or samples that show how this can be done. I’m assuming it is the same for using any Windows Forms control from a WPF application.
We do intend to build a WPF product soon, as well as one for Silverlight. Requests for both of these have been in disproportionately high demand in comparison to our other feature requests. We just started development of these controls a few months back, so we still have a ways to go before they will be released. Our intention is to have them out sometime in 2011. I will add your contact information to this feature request so that we can keep you updated on progress on our WPF control.