The 1.0.0 release is actually formerly known as the 0.20.205.1 release -- ie just bugfixes since 0.20.205.
Hadoop's been "production ready" for years - there are hundreds of companies running it in business critical applications. But some people want to see "1.0" before they move to production :) So we recently decided to call it 1.0 so that the version numbering matches the maturity Hadoop has already achieved.
Have they figured out which API they are using? You know, the old deprecated vs the new one, which last time I useed hadoop was missing features that required me to use the old API. Even though they had @deprecated all over the old API.
I think webhdfs and the option for datanode bypass on the local clients qualifies as major new features though. hftp was such a PITA and a lot of mappers are now going to go a LOT faster.
Hadoop's been "production ready" for years - there are hundreds of companies running it in business critical applications. But some people want to see "1.0" before they move to production :) So we recently decided to call it 1.0 so that the version numbering matches the maturity Hadoop has already achieved.
-Todd (Hadoop PMC)