"Backwards compatibility" as an absolute goal. This is not a bad thing per se, but it feels like the backwards compatibility requirement exists to deal with a long delivery cycle — essentially asking developers to begin developing today for the open source platform delivery in two years and the promise that the investment will be protected. All complex dynamic software hits a point in its evolution where a re-write is required. (The Linux kernel rewrote the entire VM and scheduler after about 10 years of evolution with modern architectures.) Backwards compatibility becomes the challenge. But the opportunity forward MUST be bigger than the backwards compatibility option. It needs to be managed in the community, i.e. this is a community issue and a delivery time-line issue. Think of the opportunity that Microsoft took moving from the Windows world of the late nineties to the new world enabled by NT. Think of the enormous opportunity Apple took moving from Mac OS9 to Mac OSX. Think of developing a community of innovation forward like the Mozilla world and Eclipse