How we prioritize bugs
I work on the Application Model team. In addition to the core WPF application model, we also own resource loading, deployment/hosting (think browser-hosted WPF apps and loose XAML) and Avalon's build system (our MSBuild scenarios, IDE integration with VS/Cider/Sparkle and debugging). My team also owns the Avalon component of WinFX setup. Nevertheless, Nick's post describes the guiding principles we in the Application Model team use in triaging bugs.
As we get close to locking down and shipping the product, if there is a simple mantra to how we make the difficult cuts, it is probably this: Don't let perfection be the enemy of the good.