Anyway, Has water flow been altered in any way as to better move items/creatures around?
You're right, I'd be really suprised if it had changed. The water flow isn't really so abnormal, just some of its mechanics.
I'd be surprised too. Like smjjames said, "Update blood flow/contam pushes" was something different.
The way item/creature pushing works is that items/creatures have a chance to get pushed (depending on weight or at least creature size) whenever water flows from their tile to an adjacent tile. However, this means that items/creatures in 7/7 water never get pushed, because to save on processor usage, the game "teleports" water to the edges of 7/7 areas without touching the parts in the middle. Hopefully there'll be a better solution for this later on.
Perhaps simply an averaging of vectors could be applied to the surrounding tiles between the water's starting and ending locations.
If additional water is forced into a 7/7 tile, and is teleported to the other end by pressure, even just a quick pathfind (through 7/7 tiles) between those points could provide vectors for pushing objects without having to alter the very important optimization at work here. If the number of branches is very constrained, this could even work as 'streaming outward' if a source feeds into a larger area - the vectors are going to push things from the entrance of the larger space to the exit. A bit of code could even tesselate and branch additional vectors into adjacent water tiles to create whirlpools and stagnant areas that may realistically collect fish and debris.
Using the pathfinding that already happens sounds pretty appealing. It would be great if it could just fit in like that.
I did a little exercise on this and its really simple to get interesting pushes of items in a water flow. This would work in brooks and rivers as well as the pressurized sources they behave like.
Pathfind from where the additional water enters to where it finds space. This should have some weighing towards straight lines instead of shortest path.
Along this path, create a vector that pushes objects with a force appropriate to the strength of the flow.
Now the tricky bit. When possible, create additional vectors with somewhat less pushing power to squares 45 degrees from the main vector. For each of these do the same, and each of those do the same, for a total of three iterations of additional 45 degree vectors whenever a vector enters a square of 7/7 water.
You get something like this:
Flowing from the bottom. Orange is the main flow, Green is the first branch, blue the second branch, and pink the third branch. I couldn't put too much work into arrowheads, but the visual effect is sufficient. This serves perfectly to push objects out of the flow when the stream widens and pull objects into the flow when its narrow. It creates stagnant areas on both inside and outside curves, and pulls objects back into the outflow. An object could exit and enter the main stream through here three times, flowing right out the top, or be pushed to the west bank to rest, or pulled into an eddy on the east bank.
For a half-hour idea, its quick, dirty, efficient, and realistic.