Everyone knows the story of Pope Paul VI going into the sacristy on the Monday after Pentecost and seeing green vestments laid out for him, "Where is the red for the Octave of Pentecost? he asked. "But Holy Father you abolished it." Apparently the burst into tears.
I personally would like the restoration of the Octave.
In the Orthodox world green is the colour of Pentecost, though they are less regularity about liurgical colours, churches are filled with foliage, and occassionally green hangings.
Green signifies fecundity. Thus green time, now known as Ordinary Time, used to be known as the Time after Pentecost. It was the time when the Holy Spirit was gently at work sanctifying, healing,slowly building up the Church. This is really the season of Pentecost, we look for the fantastic or miraculous but actually the Holy Spirit in most people's lives is the silent power of sanctification, causing the branches of the Holy Vine to grow, flower and fruit.