I've installed Ubuntu 13.04 in a partition on my MacBook Pro (MC724LL/A), it runs well, I've also installed Jupiter, mbpfan, Intel Linux Graphics Installer and updated the drivers. I'm booting with rEFInd, installed in the OS X partition (so to avoid the infamous 30s boot delay).

This is the stabilized OS X temperature report, while just navigating with chrome:

This is what I get from Ubuntu just upon start:

But this is what I get stabilized after using the system for some time:

The sad part for me is that, differently from OS X, now I always feel the machine warm, even idle. It's not burning, but I feel my hands siting over something that's aways warm, that's not right (I recall very old notebook models which I used that aways felt warm), on OS X, I would feel such only when doing intensive tasks. By the way, I'm not with fans running loud or something like that, just the temperature that is above, and they run loud as usual, when I start steam to play some game =)

Any tip on how to solve this, if possible? I think I've described all the software I've installed that could help with this, but none helped much...

UPDATE 1

Well, my last change was to enable EFI mode. I must do some more tests, I'm running it from battery and I think it got a good enough temperature. When running plugged to the energy source I think temperature elevates.

UPDATE 2

I think it's better after enabling EFI mode, maybe I can't get better than this, the only thing left that comes to my mind is undervolting.

UPDATE 3

I'm now using ArchLinux with general power management tools like TLP, PowerTop (with services enabled) and macfanctld. It's much better than when I used Ubuntu. This is the best upgrade I've done to this machine years back. RECOMMENDED.