It seems Google has now made available a preview program for Google Home, or is about to. As support pages for a Google Home Preview Program are now live. In fact, the support pages are not new pages and instead are simply the same Preview Program pages that were already available to those who joined up to the Chromecast Preview Program. Which Google launched back towards the end of 2016. So in reality, it seems this is more of a case of Google now expanding that Preview Program to now include Google Home.
In either case, for those hoping to secure a place on the beta program, it seems the signing up process is pretty much the same as it was/is for Chromecast. So users just need to head to the Google Home app, tap Devices, and scroll down until an enroll card appears for the Google Home device. Then on that card, tap the menu (top right corner), hit Settings, and then Preview Program. From here it is just a matter of following the on-screen prompts. One point to note, according to the support pages, if you get to the 'enroll card' point and do not see a 'Preview Program' option, then it means Google is no longer accepting new members. Although, the same pages do note that checking back regularly might be worth it, as new places do become available.
As to be expected, by joining up the program users should be able to gain access to the very latest features available for Google Home, and certainly before they become widespread available. Of course, in return for that advanced access, it should be equally expected that the features might not always be working as well as they should. Although, Google does state that the "Preview channel is updated shortly before the full push of our production firmwares" suggesting that the version made available to Preview members will be very close to the release version. If you do not own a Google Home, but do happen to own an Android TV device, then it is worth knowing that last week Google also opened up a beta program for the Google Cast Receiver app for Android TV. Which was in addition to Google+ also announcing that it is now looking for beta testers. So it does seem as though Google is making a number of new beta options available at the moment.