That roadmap is wildly inaccurate and just guesses.
Not only does 1.0 gut huge sections of code that were perfectly working under 0.9 and need to be replaced but it also replaces entire concepts (like the new object cache). There is a huge amount of work to do and I don’t envy Sam and Michael’s jobs right now. Then it will need lots of testing and debugging.
Then there is plugin stability since everything is in a state of flux. I can’t even keep up with the changes anymore, I’ve stopped updating my plugins until things settle down a bit.
Sam is currently working on trackbacks (pingbacks) now which was suppose to be the big new “feature” for 1.0 IMHO it’s a huge waste of time that could be spent elsewhere in the code but pingbacks on forums was something Matt wanted, so he gets what he wants obviously. However it will be the first feature I delete (not just disable, but delete) since XML-RPC was the #1 security problem with WordPress over the years. It’s also going to be a spammer’s delight.