Well, it looks like guys at XDA are in hurry and they recently ported the latest Android L to the last year HTC's flagship HTC One M7. Recently Google released images of developer preview of Android L for Nexus 5 and Nexus 7, guys at XDA done this work shortly after Google released Developer preview. Though port is in its initial stages that's many of its features are not working properly.
Several modifications including Kernal and ram disk are required to put up the Latest Android L on M7, One thing is sure you won't expect device to run like normal because several features are not working. Well if you are ready to take your chances and wanted Android L on M7, you can click on the source link below for the complete process. At this time features like Camera, Bluetooth, WIFI and sound are not working properly, though GPS feature is working appropriately.
Google released Android L developer preview to show developer what kind of functions they can expect from Android L, and how these functions will look like. At the end if you are ready to port Android L to your M7, Do share your feelings below.