Good idea, not sure why my own marketing department did not come up with it first! Gus has been thinking about plugin logos generally but you are right that it would be especially useful here.

Could even be used as the item icon (e.g., instead of a simple colored ball in list views), though this would have to be done carefully to avoid clashing with the Green Balls plugin. Some other TopLevelItem types (e.g., Folder) have special icons, though to date no Job types that I know of.

Otherwise icons do not make much of a showing in the UI—not used in the current New Item screen, and there is no obvious place in the sidebar (except perhaps Workflow Steps).

This is absolutely true. IMO.
+10000000

I think it is important that any feature of Jenkins Pipelines/Workflow can take advantage of also be available to all other plugins. I think the first step to this is to enable item creation types to have icons and for items in general to have categories. tomjdalton, let me know if you think this might be moving the needle in the right direction: https://youtu.be/LEKMMZYg9B4

...also, as Jesse mentioned, new additions are on the way for the plugin website that will give plugin authors a place to add an icon. I think you are right, this isn't only an issue of self promotion or superficial decoration, but that icons actually help people scan a list for the items they want and care about.

greiber - I'm easily pleased. I'm happy if I've got an icon for the pipeline stuff that I can put in presentations.
Looks like it is some sort of pipe

PR 375 is adding an icon—is this intended as a general logo?

gusreiber It seems the PR #375 was merged.

https://raw.githubusercontent.com/jenkinsci/workflow-plugin/98a1afc7748398d08df1bdf068e038baee353934/job/src/main/webapp/images/48x48/pipelinejob.png

...so not sure how well this will do in presentations, as it is pretty small.

Pipeline items have icon