With room temp at 27C, that does seem too bad, i had 12-15 7200.10s in my office for a a while and they were that hot, i recently built a new server and server in the basement, and under hard load none of the drives go over 30C..... I would say your room temp is high, nothing else....
I've heard the 750's do run a little warmer than usual and from my experience Seagate drives run warm to begin with. My 500 gig Seagate runs warmer than my WD drive by a couple degrees. Right now room temp is 25c and the Seagate is 34c.
I wouldn't be surprised. Fast platters, high speed precision parts, its going to add up to temps. When I stacked 2 x 250 gig Diamond Maxtors, in an ATX case that was meant to hold them like that, I kept getting BSODs, crashes, data corruption.
As soon as I spaced them out amongst the case, no more errors, it worked well. I shudder to think of how hot the 1Tb drives run under load. You'd need active cooling.
My seagate 750GB drive in a 4-in-3 enclosure with active cooling idles around 45C. IIRC the google HDD survey found little correlations between failure rate and temperature: http://labs.google.com/papers/disk_failures.pdf
Once you go above 45C there seems to be a stronger correlation, anything below appears to be fine.
Hdd#1 Temperature 38 ºC
Hdd#2 Temperature 35 ºC
Hdd#3 Temperature 36 ºC
Hdd#4 Temperature 39 ºC
Hdd#5 Temperature 39 ºC
Hdd#6 Temperature 39 ºC
These are all Seagate 750gb drives in my Silverstone TJ-09 running off of my Areca ARC-1231ML Raid card. 1-3 are in the lower cage and 4-6 are in the upper cage. I have a quiet Scythe S-Flex 120mm fan installed. I wish the temps were a bit better, and I'll probably throw a higher CFM S-Flex in there. The cages themselves are pretty restrictive and the fan is sandwiched between the two cages not providing the best flow possible.