Sitellite itself isn't affected by the upcoming DST changes, however several software packages that Sitellite relies on may be. These include Apache/PHP, MySQL, and the server operating system itself.

For your operating system, you should contact the vendor to find out about updates.

For Apache/PHP, once your system update has been applied, just as with any change to the system date/time information, make sure you restart the Apache daemon so it re-reads the system info. Usually that's just a matter of executing the following command:

apachectl restart

For MySQL, this may be all you have to do, however there may be more to syncing the date/time info between the OS and MySQL than that. The links below should provide the information needed to complete that task.

Based on the links below there may be more to syncing the two than just a restart.

A relevant post from the MySQL Internals mailing list:

http://lists.mysql.com/internals/34139

The mysql_tzinfo_to_sql page:

http://dev.mysql.com/doc/refman/4.1/en/mysql-tzinfo-to-sql.html

MySQL Server Time Zone Support (MySQL 4.1):

http://dev.mysql.com/doc/refman/4.1/en/time-zone-support.html

MySQL Server Time Zone Support (MySQL 5.0):

http://dev.mysql.com/doc/refman/5.0/en/time-zone-support.html