From what I have read very few of the crews saw anything or even knew the invasion was on until they turned on their radios the next morning. There were 10 separate targets that night, and they were all marked using Oboe by Mosquitos of 105 & 109 Squadrons (25 each). The Oboe crews were not told that the invasion was happening that night, although it was a record number of targets for them and also a record number of crews going out.  I don't believe any  Pathfinder or Main Force crews were told at the afternoon briefings that the invasion was about to begin with the bombing of those coastal batteries.
 The first target attacked was St Martin de Verreville -Zero hour was 23:50 on June 5th and the last target was Ouistreham- Zero hour at 05:05 June 6. There was thick cloud over over the targets which only began to break up around sunrise and the crews marking near dawn could see the invasion fleet through breaks in the cloud. My father was a Navigator in one of the 3 Oboe Mosquitos that marked the coastal battery at St. Pierre Du Mont (Pt. du Hoc) at 4:50 am (which was sunrise) and he could clearly see the invasion fleet even though he marked from 30,000 feet. He did say it was quite a sight and there was no question that the invasion was underway.  
Most of the Oboe crews had landed from their ops before he took off at 03:25 am and except for the crews marking the last couple of targets none of them had seen anything or were aware that it was D-Day. 
Dave Wallace  

-- Edited by dawallace at 15:07, 2008-06-09

-- Edited by dawallace at 15:37, 2008-06-09

Nearly a couple of weeks late but the link below will take you to the D Day Instructions issued to the Tempsfor Special Duties Squadrons.
Sorry the quality is not brilliant but I hope you find it of interest.

http://www.geocities.com/fk790/Tempsford/D_-_Day_Instructions.html