I keep an air filter near my desk as well, and though it seems to help a little, it doesn't eliminate dust completely--at all.
I've had my iMac 27" mid 2010 for about a year now and it runs a little bit hotter than it used to...
Just an observation, but we are coming out of the summer months. Has the ambient temp been higher?
That's something to bring up as well; my machine runs around 60 or so at home and only 50 or so while at school, due to the colder classrooms. Right now I'm in a coffee shop and it is a comfortable, 80 F degrees in here. Machine is at 67 C.
I'm in Florida BTW; later in the year and the beginning of next when it cools off, I'll be able to just run everything without AC or a fan and have cooler temperatures overall.
Wirelessly posted (Opera/9.80 (iPhone; Opera Mini/6.1.15738/25.823; U; en) Presto/2.5.25 Version/10.54)
Dust sucked from the fan inside the screen?! No way... When you remove the glass the dust could remain inside but not from the fans during normal use, the fans are inside/rear the lcd panel and the glass "close" it from the rear, i've never hear someting similar (yes a lot of people have found dust inside the glass but there is inside from the first start, not after 4 months)