Not sure when this happened, but as of today, i was explaining the "D" mark next to the check of a SMS message meant it was delivered, and as I went to show an example I noticed that my phone no longer shows them.
I did a search about it, and it appears that back in 2008 some regions lost it as a possible privacy issue, but on the last few post of those threads, it said it was re-implemented, so I'm not sure if this is the case for me now in 2010.
Working fine for me CT - Home State, and in CA for vacation and worked in both states.... But I did notice it only shows when sending to other Verizon Phones...
Verizon had turned that off in some markets for a little bit. But the instant negative response prompted them to turn it back on. Now some phones have the option to turn it on/off, and many of those phones come with it set to off as default.