Sounds like they're just tired of updating beta version numbers. "We've been working on it so long, let's just call it finished, we might get to a 2.0 version, don't know if that means anything or not..." Sunbird/Lightning with CALDAV had a lot of potential as a free alternative for exchange server for sharing calendars for small business. We set it up at several clients and they liked it pretty well, but had occasional problems with calendar files getting corrupted between computers, or getting too large and slowing down the clients. Then they released version 0.3 which broke the caldav function, and wasn't fixed until recently, if at all. I lost track of it and haven't tried it again recently. Most people who needed the functionality moved to Small Business Server. Shame they didn't have more development resources, they could have gotten to this point 5 years ago.