The most surprising thing to me in the OP was seeing that Octopress users had been updating their sites all this time...I frequently checked back on the Octopress blog, and then the Git repo, to see how to go about doing that. I tinkered around playing with the dev branches but didn't know enough to get around their hiccups. Finally I gave up on it and just went to Jekyll, which was definitely a blessing in disguise, as it let me figure out more of the process of static site building, with fewer abstractions and conveniences in the way.
I don't know if I'll ever go back to Octopress -- I'm a devout Middleman user now -- but the direction it's taking seems to be the right one, and I'm amazed that the author, these past few years, is still cranking away at what could easily just be a legacy, soul-sucking project -- given the size of the userbase and the number of dependencies/upgrades involved in changing the code base.
For what it's worth, I'm also a huge fan of Middleman. It's a great project and I use it for some things too. For a while, when Jekyll was in a dry spell, I considered building Octopress tools for Middleman as well, but in the end I prefer the simplicity of Jekyll.
Middleman is great, but it's too much like the view layer of Rails. To me, Jekyll feels more like the native web.
But of course, that doesn't mean you can't do incremental rebuilds. If the data is older than both the HTML and the template, then there's no need to rerender. More generators should support this, either internally or by making it easier to run them as part of a Make build.
Not quite the admin GUI you're looking for though; it's more for lowering the barrier to entry.
NetObjects Fusion had some interesting features and ideas. My first non-intern job was with a company that did e-Learning materials. Our products were basically self-contained websites, with video content and scripted subtitled text, distributed on CDs. This was 2002 or so, so it was super bleeding edge then.
Our entire infrastructure relied on the extensive scriptability and plugability of NetObjects Fusion. We had an entire authoring system and video production pipeline that would allow NetObjects to generate pages for the videos with templates, all things needed included. All you had to do was drag the video player into the page and set the right property, and our build system would handle everything else.
The process was so automated on the technical side that it allowed the task of actually assembling the sites themselves to be farmed out to University students with little technical training. Although, speaking as someone who was initially hired as one of those "production workers," we were paid very well relative to other traditional college jobs and the work, while sometimes tedious, was often interesting and fun. I got to learn so many random things - how tires are made, how the propellant for the Space Shuttle's SRBs was mixed, etc.
Even now, I can still, a bit fondly, remember the hierarchical layout of NetObjects, with it's little yellow and black shields representing pages.
It was also a great company to work for. The owner was a business professor full time and this was his side project. We were always small, and him and his wife always took an interest in all the students that worked for them. Getting a home-cooked meal and a night of poker once a week was a nice perk for a poor college student.
The cool thing, though, was there was no pressure to stay. They knew we were students, they knew we were going to graduate eventually and take jobs elsewhere. It was a mutually beneficial scenario where they got relatively cheap labor (at the time), and we got good experience before heading out into the world.
I ended up staying on there for another 3 months or so after I graduated before taking my first full-time programming job. A big part of me landing that first post-college job was due to experienced I gained working in that environment. First as a lowly production worker, then advancing to graphic design, administering the network and programming plugins and scripting for NetObjects.
So I suppose my career would probably look very different without NetObjects Fusion.
EDIT: It doesn look like it's available for linux though...
If you find a workflow that works for you, post an issue on GitHub and maybe I can help automate parts of it. If it's just about adding YAML data, the new post templates feature of Octopress should take care of you there.
EDIT: Whoops, there's now even a directory listing static site generators in different languages! https://www.staticgen.com/
HERE HERE! Can't wait for this to be out!