What functional differences exist between WPF and WinForms WebBrowser control?

WPF WebBrowser control looks great but knowledge accumlated over time about WinForms WebBrowser is substantial and it's hard to ignore work like csExWB. It would be nice to know what functional shortcomings or advantages exists in .NET 3.5's WPF WebBrowser control over WinForms WebBrowser control. In particular, is it possible to build csExWB-like functionality on top of WPF WebBrowser?