Hi I have a slimline 120GB with PlayTV (I don't know whether you have this in USA but it is an official Sony TV tuner like Tivo but for PS3). Whenever PlayTV records it turns the PS3 on and it gets as hot as it would when you are playing games. I probably use PlayTV from 5pm to 12, so in this time my playstation is always on. Most of the time it is recording whilst I'm playing a game, so its doing double to work (and I frequently have an HDD and the controller plugged into the USB ports).
My question then would be what reputation does the slimline have with overheating? Are there any cooling fans that someone can recommend?
I know that when it first came out, there were a lot of fears because the disks were getting hotter than with a phat PS3...but that seems to be related mostly to the HDD placement. So far, I have not heard of any heat related slimline failures that were not the result of poor placement (like in a closed up cabinet)...but then the slimline is still rather new.
I would just keep it well ventilated...and if it gets too hot for comfort, you can always do a fan fix. Also, given the amount of time you run the system, it might be advisable to just leave the thing turned on all the time...most heat-related PS3 failures do not happen while the system is hot, but rather, while it is cooling back down after being turned off.
...And no, we americans don't get PlayTV...even sony can't play by our insane, dmca-inspired rules.