Contrary to today’s issues with the PS3, your trophies are safe providing you recently synced your trophies to your PSN account. All your trophies are backed-up with your PSN ID so if you did lose some trophies, resyncing with the PSN will restore any lost trophies. However, if you earned any trophies since your last sync and you were affected by today’s events, then your trophies may be lost.
If you are unsure on your last sync, Sony recommend not turning on your console until a patch is available. But if you have already turned your console on and were affected by the date bug, you can check your trophies online to see what you may have lost (if anything). All the trophies listed online will be restored on your next sync.