The Windows Forms combobox control contains a nasty a lot of people who will try .NET 2.0 applications on .NET 3.0 will run into: the Sorted property makes comboboxes unable to bind to data: they stay empty. This is particular bad, because any solid working application for .NET 2.0 using comboboxes in a databinding scenario (and I estimate a lot of applications fall into that category) which uses the Sorted property to get sorted results will run into this problem, and it has huge consequences: any user who has .NET 3.5 installed will run into this, no matter what you defined as supportedRuntime in the .config file of your application.
I've logged a bug in Connect with a repro case (very lame form). Setting Sorted to false fixes it, but of course, in already compiled applications or in applications with a lot of comboboxes, this can be a real problem. If people have workarounds for this, please step forward. 