As you may or may not know, everyone trying to update to Windows Phone 8.1 via the Developer Preview got the dreaded 80183309 error, which means "The update was download, but couldn't be opened".
I took a risk and installed the Russian ROM people were talking about at the Microsoft Community and check the post by FedorMaslak - translation required Russian - English) on page 43.
Here is how you do it:
Step one - Flash the ROM using the tools in the forum entry above.
Step two - Download General Distribution Release 2 (GDR2) OTA via phone update
Step three - Download Preview for Developers
Step four - Activate the Preview for Developers and install GDR3.
Step five - Once installed, you will see Update 1/2 installing on your device, this is for preparation for WP8.1
Step six - Check for updates and Windows Phone 8.1 will install!
I have made a video with WP8.1 running on the Huawei Ascend W1, which is available by searching RYANODONNELLUKF on YouTube.
(Sorry, XDA-Developers wouldn't let me post outside links...)