1 billion seconds is a significant birthday or anniversary, being about 4 months shy of 32 years.

1 billion seconds is 31 years, 251 days, 13 hours, 34 minutes, 54.7843 seconds. But note that these are 365-day years, so you have to adjust for leap years. Remember, a leap year adds 1 day at the end of February on years that are divisible by 4, unless they're also divisble by 100, except when it's also divisible by 400. So, 1900 was not a leap year, but 2000 was.

If the event time was around 10:30 am, you may need to worry about whether the 13.5 hour remainder puts you over onto the next day. If you're really close, you may have to worry about leap seconds, of which there have been 22 added to the calendar since July 1, 1972. As of 2004, this is the complete list of all of the leap seconds:

ftp://tycho.usno.navy.mil/pub/series/ser14.txt

0 36204 01-01-58 Beginning of Atomic Time

1 41499 07-01-72 Effective at 0 hours UTC of the MJD

2 41683 01-01-73

3 42048 01-01-74

4 42413 01-01-75

5 42778 01-01-76

6 43144 01-01-77

7 43509 01-01-78

8 43874 01-01-79

9 44239 01-01-80

10 44786 07-01-81

11 45151 07-01-82

12 45516 07-01-83

13 46247 07-01-85

14 47161 01-01-88

15 47892 01-01-90

16 48257 01-01-91

17 48804 07-01-92

18 49169 07-01-93

19 49534 07-01-94

20 50083 01-01-96

21 50630 07-01-97

22 51179 01-01-99

I will be 1 billion seconds old early in the morning of July 20, 2009. That's 7-19-2009+h-hour+13:34:39, where I think h-hour is around 11:30am.

My wife will be 1 billion seconds old on 3-10-2008+h-hour+13:34:38

My brother will be 1 billion seconds old on 1-09-2007+h-hour+13:34:37

My parents will be 1 billion seconds married on 7-30-2006+h-hour+13:34:36