XDA Senior Member djtonka posted a discussion thread for those who have the Nokia 710 and 800. So far, it’s mostly users confirming that the update is working in a myriad of countries and models. So far, no one has reported any problems. It seems to be up and working in most regions, and no one is complaining that it doesn’t work yet. However, there are a lack of flashing instructions. If you don’t know how to flash firmware, check out this thread by XDA Senior Member sutt359 for firmware flashing instructions.
If you have the Nokia 610, all your instructions come in one spot. XDA Senior Member safariking posted a thread getting WP7.8 installed on the Nokia 610, as well as discussion and support for those having issues. Like the 710 and 800, 610 users have confirmed that the update is working in most regions. Therefore, installing is just a matter of finding your region, downloading, and installing. These instructions also work for the 710 and 800, if you need further help installing the update.