At some yet unknown time between Wednesday noon and Thursday noon (28-29 Nov 2012), the first Bitcoin block with a reward of only 25 BTC will be found.
To commemorate this once-in-a-4-years-time event, the hardcore Bitcoiners are going to gather for a toast.
The short notice for this event is part of the stochastic nature of the process.
Most likely we will not be able to meet at the exact time of the halving, and so the meeting has been scheduled for a generic 7 PM (on Wednesday). If we see that hitting the event time is feasible, we may tweak the meeting time.
Both the time and the location are subject to change, so check back for updates. And don't forget to RSVP.
Venue website: http://www.rol.co.il/sites/resh-lakish/
Update: If you want to be there when the block reward halves, follow these instructions:
Look at http://bitcoinclock.com/ for the estimated time until the halving. This changes rapidly so look at it frequently. Try to be there an hour before the estimated time, to prepare and to account for variance. (But the venue opens at 18:00, so no earlier than that.)
As of Wednesday morning, the halving is likely to be anytime between 16:30 and 21:30.
Update 2: The halving is likely to be before 18:00 so we won't be able to witness it together. You can come whenever you want, I (Meni) will be there from about 18:30.