The Nexus 4 is nearly turning two years now and hence the updates are starting to slow down. During the I/O 2014 keynote, Google unveiled Android L. Shortly thereafter, the Developer Preview was released for the Nexus 5 and Nexus 7 2013 but the Nexus 4 owners had their hands empty till yet. That has now changed as XDA Devs have did what they are famous for once again, the PORT has been successfully achieved as XDA Senior Members sykopompos and defconoi came through with the L-Preview for the Nexus 4.
The XDA members claim this port to be fully functional and worth a daily driver but trying it yourself might be the best way to judge that. There will be some Bugs in this port as it is in early stages of development but that isn’t something a Regular Custom ROM user will mind. On the other hand if you are someone with very little to no knowledge about custom ROMS and Ports then it might not be a suitable way to go for just the purpose of getting a Latest Version of Android, not yet !!
You can have a look at the Original Development Thread and progress in the desirable manner, also if you are going for this port on your Nexus 4 then please review it in comments section to help us make a list of bugs and issues for the users who are a little less bold than you might be.