Since receiving the Nether update yesterday and staring to play on our Realm (updated AFAIK) I noticed that in a few of our farms that rely on water streams to transport items the dropped items are no longer flowing correctly.

The items appears to "stick" to the left side of the stream and bunch up in the corner.
This is most visible at point where they should (and have done pre-update!) flow over pressure plates into the next water stream, these are all built on packed ice blocks.
So far I have noted this behaviour on a bamboo and guardian farm. In the latter some items do unstick however I can walk around and inspect the water streams (all encased in glass) and see items and XP orbs are pretty much each pressure place point.

I did notice on the bamboo farm, where the water stream is a raised glass-encased over hoppers, that the water stream itself (when view end on) appears to slant from left>right, so the marginally shallower end is where the items tend to flow. In this instance, I noted bamboo items stacked there that weren't even being collected by hopper underneath.