When Unix Clocks Hit 10-Digits Will Anything Break?

dannycarroll asks: "I've not heard this mentioned yet so I'll bite. This weekend (depend on where you live) the Unix system clock hits 1.000.000.000 seconds since the Unix Epoch. I heard about one or two applications that are vulnerable to a date overflow but I am wondering how many more are out there, unknown. It's not the Y2k bug and consequences are far from it, but it seems to me that there has been too little attention paid to this potential problem. As an example, I wonder how many Perl scripts out there use 9 digits for the date-stamp field instead of a delimiter?" I've been hearing about this from several different directions and it took me by surprise. I would think that most programs out there are using time_t or at least 32-bit integers by now if they are storing seconds-since-the-epoch (you would think we actually had learned something from the Y2K chaos). Are there any well known programs that might break because of this?