Already have it. For folks who don't have it, and have Zune keep sayin the phone is up to date, then do the following:
1. Start Zune
2. Turn off Data connection and Wifi on the Phone
3. Connect the Phone with the PC (USB)
4. Start the update search in Zune
5. About 3 seconds later (has to be precise; try again if needed), disconnect your PC from the internet (Turn WLAN off).
6. Zune should find an update available. It will vary depending on your current version. (If you are on NoDo (7392), then you should see that Zune finds the pre-beta (7403), and consequently you'll see 7720.68, aka Mango. Zune will take you through all updates, to get you all they way up to 7720, so be patient!)
7. Connect to the internet again and install the update(s).
This is not a "hack" per se. Zune's update check process consists of two phases: First it checks if there is any update available, once it finds it on Microsoft's servers then phase two starts, which is when Zune checks for carrier/OEM approval. According to this very article, Microsoft has told carriers not to release it to everybody just yet (only 10% of customers), but instead send it in batches throughout the month. All this little trick does is prevent Zune from ever asking carrier permission, and stop it from determining if your phone is part of that 10%.
What Zune version are you using? Make sure it's 4.8.2345.
Also, if it fails, not just hit the update option in Zune to try again. Make sure to disconnect the phone, and connect it again to try it again. Every time.
When you check for an update, a bar in the middle of the program pop us and fills up to the right; I timed it so that as soon as that bar hits the end, at least a second later I disconnected my wireless.
It actually took me quite a few tries to get it, just like yukka, but I eventually made Zune find the update in under 5 min or so. Just gotta keep trying.