Maybe I'm not the best person to go saying this here but I just can't help myself from doing it...
Has IPv6 been accepted by the whole industry market players, or at least a big majority?
Is it a finished product?
And I'm not talking about it's concept that has beens ready for many years already.
I don't mean to underestimate Cisco or anything but they're the only ones clearly supporting IPv6.
No other big market player has been so actively interested in implementing IPv6 in their products as they have.
That's not true, virtually every major commercial networking vendor has full IPv6 support. The standards have been final for quite some time. Every major OS includes support, as do all the big name network devices. The US government has mandated IPv6 support on everything it purchases pending a forced change by 2008 or 2009 (I don't recall for sure, somewhere around there), and those sales alone were enough to push all the major vendors to include support.
How widely and quickly we'll see businesses and ISP's switch over is another question entirely. Given that the IPv4 address space shortage isn't as bad as it's sometimes made out to be, it'll probably be a while. At least in the US for sure. Asia will likely be the first to see major deployment, since address shortages are much more of an issue there. In the US, most ISP's have enough IP's that they won't have to worry about IPv6 for a very long time. For example, my cable ISP has several million IP's registered in my city, with only a population of 700,000. They have something like 5-10 IP's per person, which is more than I would ever envision them using given there are at least a couple dozen other ISP's here.
Granted, IP address shortages isn't the only reason to use IPv6, but it is the factor that will probably eventually drive ISP's, and hence businesses and homes, to IPv6. I expect ISP's, especially residential ones, to hold out as long as possible due to the difficulty of getting users to do something to their machines/routers as relatively difficult as a switch from IPv4 to IPv6. (most of these people are lucky to be able to figure out how to turn on a PC)