What strategies have you used to avoid scene scripting and which ones would be of use to people WRITING adventures down?
My answer applies to homemade adventures and would at the least require some polish before it would be truly useful to published adventure authors.
Bullet points are your friend. They help you focus on what's actually important without getting bogged down in details. They keep things succinct, maximizing your flexibility when you're actually playing. They discourage a level of detail that devolves your encounter idea into a scene script.
When I start to work on an adventure, I usually write a page or so of notes that set up the background of the adventure--what has gone before, and the real scoop on what's happening now.
Then I write a few bullet points on what the adventure should accomplish as relates to the campaign plotline (things like "introduce this NPC who might become an ally later" or "give the heroes a chance to learn more about the mcguffin's backstory")
Then I write a few bullet points for each of the major NPCs or factions associated with the story: what they are trying to achieve.
Finally, I write a few bullet points for encounters I expect to occur in each of the three acts, one bullet point per encounter. Generally speaking, at this point the later acts have fewer and vaguer encounters than the first act, but I try to visualize a likely course of events and usually have an interesting set-piece in mind for the climax or a few key scenes (often the turning points between acts, which include plot twists or major reveals).
Each encounter follows a similar outline, on a smaller scale. Usually one or two sentences setting up the encounter. If I know when and where the encounter is likely to occur, I bullet point the date, the weather, and the phase of the moon. If the encounter is tied to a specific location, I do a few bullet points of "boxed text," but I usually keep that in my head. Then a few bullet points about what the NPCs/monsters will do proactively, and how they'll respond to the most likely player actions. I also try to come up with all the little details that might be relevant (the names of minor NPCs in the scene, for example) even if they're unlikely to be used, because those details really bring the game to life, and I find it hard to come up with them on the spot. (Sometimes I think writing the little things down is more important than the major plot points or even stat blocks--I can fake those things more convincingly than the details!)
Follow that up with necessary supporting data--stat blocks; who's who lists of NPCs, etc., and you're golden!
Now here's the kicker: I usually only write down enough encounters to take me through the next game session, with maybe a couple extra to spare in case the players make better time than expected. After all, I have the single bullet points in the overall outline as my road map. When I'm preparing for the next session, I review my overall bullet points (what the bad guys want to achieve, the three acts, etc.), and I detail the next few encounters as above. Because I haven't already committed to too much detail, these encounters can be designed in reaction to what has happened in the story so far.
I guess the bottom line is this: Don't write yourself into a corner. Keep things loose and flexible. Nail down the details that have nothing to do with player decisions (NPC names and the like), while keeping the rest of it vague. Allow yourself to develop a lot of the content at the gaming table, instead of beforehand. Give yourself a road map, but don't plan any details too far in advance. And make liberal use of the bullet point!
(Oh, one more thing: Bullet points are also much easier to reference in play than dense running text.)