First of all, I'm sorry NineSixty hasn't been developed further at this point. I had plans to improve it as a base theme for version 2 but my priorities were lying elsewhere. It also didn't help that I lost some interest but I will definitely pick-up where I left off. This doesn't mean I see 960.gs (the original grid system) as less relevant. In fact, I've been using it in other projects. It's just my role in creating a solid base theme that has been waning.
I do think the NineSixty Drupal theme is less relevant today since anyone with some experience can integrate 960.gs into their themes from scratch and there are plenty of alternatives that add more flexibility and are better maintained. It was never my intention to add too many user friendly options and this will continue in version 2. New features will target theme developers only.
With that said, NineSixty v.1 will be updated for Drupal 7 for those moving onto the new version of core. A new release will be posted to coincide with the Core release on January 5th. Beta versions of NineSixty v.2 for Drupal 6 and 7 will start appearing about a month after.