From what I've read the PS3's power supply is universal, they just change the voltage on the case depending on what region it's sold in, I haven't personally tried it myself though.
I know when I open my power supply it distinctly says
"AC Input 100v-240v~" which would indicate that it is universal.
But it's up to you in the end of you want to take the risk, or just buy a new power supply when you get back. No clue if it's the same for the slim though.
*edit* I should clarify that the ps3 actually has multiple power supplies. Some of them are Universal, some of them are not, so unless you want to open your power supply and look for yourself, you might be better off buying a new pwoer supply when you get there.