5.5 was just released with the boost as a free update for existing 5X users. 6 Should have many more features. IF they are going to announce 6 it will be around the holidays this fall/winter.
Even though Edius is still my main NLE editor and love it with it's short comings , I feel it needs abit more 5.0 to 5.5 there is is no great insentive for me to upgrade from 4.61 , If i see what Adobe is offering me now in CS5, I can only hope that 6 has more meaty features.
While editing DV i was pleased with Premiere CS2 and there was no need for me to upgrade at all...
Same to Photoshop... The new features are nice... but most of the time i'm using my "standard-procedures" while editing a photo... so I'm fine using CS3. But thats another story...
What matters to a video editing software in my opinion is: stability, input and output capabilities and a good workflow.
I dont think the step from 5.5 to Version 6 will be that huge... For me - i'm absoulutely fine with 5.5 for now and this will be my nle for the next time/years...