I was always disappointed that he didn't return in ghostly form for either AOTC or ROTS, the way Obi-Wan did in ESB and ROTJ. I always thought that he must have been sort of washing his hands of the role. In particular, the scene at the end of ROTS where Yoda revealed to Obi-Wan that he'd been in touch with Qui-Gon always seemed to have be a bit hastily inserted, as if to make up for an actual cameo from Neeson. His absence meant that the line didn't really work, IMHO.
But given that Yoda told Obi-Wan about this at the end of Sith and given Obi-Wan's apparent surprise, doesn't it contradict the cameo in TCW? Okay, admittedly, for all we know, Obi-Wan went on to tell Yoda 'Hey, I had a vision with him too' but in ROTS, you did get the impression that this came as something of a surprise to Obi-Wan. Surely if he'd already heard from Qui-Gon, he'd have been a bit more blase about Yoda's announcement?