Nintendo of America is distributing a special access code for a demo of Tomodachi Life to a select group of Club Nintendo members who have achieved Platinum status (those who have earned 600 Coins or more during the current fiscal year). The demo, entitled Tomodachi Life: Move-In Version, will allow you to transfer your Miis (as well as a special bonus item) to the full version of the game when it debuts on 6th June.
Not all Platinum members will get a crack at Move-In Version, however, as the verbage "select group" indicates; the emails also seem to suggest that those who have Animal Crossing: New Leaf registered have a higher chance of being selected for the demo distribution.
It's currently unknown whether or not a similar distribution is happening in other parts of the world — 'Platinum' status doesn't even exist in Club Nintendo outside North America — but hopefully a demo of some sort will make its way to the European and Australian market sooner or later. Give us a shout if you received the special email from Nintendo, and let us know how excited you are to try the new demo!