hs_err_pid.log files used to report date and time of the crash and 
how long the process had been running by the following two lines:
(The following was created by a 1.4.2_06 release.)

Local Time = Tue Jan 09 15:30:42 2007
Elapsed Time = 8136

Beginning with Java 1.5.0 both pieces of information have been dropped 
from the hs_err_pid.log files, unfortunately. While the "Elapsed time"
item may be negociable, the date and time of the crash is regarded 
vitally important for matching other pieces of information, e.g. 
crash dump files. The only information available is the time stamp of 
the file "hs_err_pid.log" itself.

The time stamp of the hs_err_pid.log files however could get easily 
modified. For example, files are sent around by mail, especially sent 
into Sun Microsystems for service reasons. The only way to prevent 
the date information from modification is zipping the file/s into an 
archive, which will need to be requested explicitly.