Unicode has been with us for a while now. The first standard was published in 1991 CE with Unicode 1. Now we have Unicode 4.1.0 with Unicode 5 in beta. The IETF now specify that protocols must use UTF-8 RFC 2277) and it's already the standard encoding with XML and hence XHTML (barring some protocol hiccoughs with MIME types and default character sets).
The list is incomplete of course. Let me know what else I should be adding.
And then there's the dark side.
Site developers clearly still have a lot to learn about Unicode. Issues with PostgreSQL (now fixed) has also shown up problems with site design systems like PHP. These issues are just the tip of the iceberg. It is this continuing aspect of encoding misunderstandings that is slowing the adoption of Unicode.
As for me, I'm trying to do my bit by using outrageous UTF-8 URIs to see what I can break. I've broken a lot so far, but as everybody I've contacted has either fixed and updated their systems or is waiting for their next roll-out I felt it unfair to name and shame. If you want to test your systems then see how you get on with linking to pages like สงกรานต์—drop me a line to tell me how you get on.