So people clap your hands
Despite the demise of Be, the BeOS remained popular among its fans, of which I was one. I joined the Be community very late in the game, somewhere 2001 or 2002, but ever since, I'm hooked. Applications were still updated, new programs ported, but in the end, it became ever clearer that the BeOS as it existed in 2000/2001 was having ever more trouble running on modern hardware (not even a code leak of a more recent version could help). What was needed was something to bring the BeOS up to speed, to allow it to continue to be developed for modern hardware.
But how? BeOS is proprietary software, and as such, you can't really improve any of it in a way that is considered legal. To remedy this situation, the OpenBeOS project was started in 2001, which aimed to recreate the BeOS as open source software, using an MIT license. The initial expectations by ex-Be engineers weren't particularly high. In August of 2001, after talking about it with several ex-Be engineers, Eugenia presented the following conclusion:
It turns out Eugenia was indeed right when it comes to the years and years it would take to reach an alpha state, but the conclusion that the project would go nowhere turned out to be somewhat off the mark. It has been a very difficult and rocky road, a long road, but here we are, about eight years after the project's creation, and I'm looking at my computer screen, where the first Haiku alpha is merrily chugging along.
Why has it taken so long? Well, obviously, it's not easy to rebuild a complete operating system, without having access to the source code, in such a way that it retains binary compatibility, while still updating several aspects of the system, and fixing loads of bugs. At the same time, it has to run on modern hardware as well as 'old' hardware, and you're all doing it for free.
On top of the practical reasons why it took so long, there's also a more philosophical reason. The Haiku team members and developers are very aware of the concept of public image, and are very careful about promoting the project as being stable or usable. With the release of an alpha, the team is making certain promises about quality and stability, and they want to ensure they can keep those promises. In addition, the geek world is filled with former BeOS fans, and a lot of them will use the alpha as their first acquaintance with Haiku, and the team wants to leave a positive impression. They don't have the luxury of pulling a KDE 4.0.