Yesterdays video by CCP Guard confirms what CCP Fallout said a while ago on Twitter: engine trails are being worked on and will be reintroduced to EVE at some point after the Winter Expansion. This is a very good news for vets like me, I really loved the engine trails when a big fleet warped in or out, or when fast ships zoomed around on MWD (check out No Other Destiny (1:16) or EVE Never Fades videos (1:54, 3:09) if you want to know what I’m talking about).
EDIT: Engine trails will be included in the Winter Expnsion after all. Good news!