I personally think if you're going to build a room specific for ht, I would tend to go the route of building a 4x2-4x3 room for housing the ht gear in especially if you like using monoblocks to power your speakers..

even using using a multichan amp in a closet arrangement I would still consider a sideways ventilation system between equipment where possible..
ht
Passive cooling isn't always the best even if it's the only option you thought of at the time of install, nothing is ever cut and dry when you think about installing something, there is many ways to build a room for ht and a space for ht gear, we all cut corners to save money... not always for the better I might add..

when I look at ht I look to more than 2 years out of service on what I buy as I can't blow the cash to keep up with the jones of this world so I buy something to last far a while atleast..

While waiting on my Audio cabinet to be built, I purchased A cooling fan system from http://www.coolerguys.com/840556090113.html.
My cabinet will be 70"W x 24'H x 24 "H. The two end compartments will hold my gear, while the middle section will house the center speaker and a lower drawer. A cooling fan system is my only option with space being so tight.
So for the benifit of those looking for a quite fan system ,I have already recieved and demoed the fan system, and can tell everyone is is very very quite . From 5 ft away I can not hear it at all. It has a themostat for each fan, comes on at 86 deg and shuts down at 81 deg .

Because a picture is woth a billion of my words :This is what I have being built , trying to stuff all my gear into those two compartment is problematic , but it will all fit.
I am having it built localy . I am able to change a few things this way , like dept and the width of center compartment.
http://www.standoutdesigns.com/store/pc/Horizon-N702-Plus-Solid-Wood-TV-Console-10p322.htm

Two thoughts to keep in mind when integrating these fans into the cabinet: exhaust requires intake, and noise will change when you increase the static pressure on the fan. For the first part, be sure the cabinet maker provides ways for air to enter so these fans can effectively discharge air and cool the equipment. For the second part, be aware that the noise made by the fans sitting out in the open will be at least somewhat less than the noise they make when in an enclosure that makes it harder for them to draw air. You'll get some sound attenuation at the same time, which will help make up for some of that, but it may not make up for all of the extra noise - especially if the fans are obstructed.

On the bottom shelf , at the front on each side. there will be (2) one inch slots cut, five inches long each . There will be (3) 1 3/8" holes cut for wiring on each side in the back, in which I will put http://www.closet-masters.net/flexi-topgrommets.aspx , thereby attempting to make sure the air is drawn from the front of the cabinet as much as possible. I realy do not think I will need these grommets due to the fact that there should be enough cables stuffed through each hole up to restrict the air considerably.
(These fans are each ratted at 46 CFM ). I know some air will be drawn from around the doors also, which I believe is OK as long as most of the air come from the bottom up The fans will be mounted to the cabinet using rubber backing material to absorb some vibrations.
In therory , I believe it should be OK, but I won't be shocked if I am wrong.

With those two 5"x1" slots and some assorted other leakage, a 46CFM fan in a single cabinet will produce around 650 ft/min of air velocity at the intake slots. That's about twice what we design transfer air openings for in commercial installations, but still a slow enough flow rate that it shouldn't create noise of its own.

Posted for your edification:
Worse Than Assembling 100 Bookshelves at Once

I know how many folks that visit these forums seem to like seeing firms smack their face into the pavement, so to speak, and sounds like the good people at Ikea are doing so...

Making usable A/V equipment is MUCH HARDER than making furniture that comes out of a flat box...

I just read the Uppleva report and why would anybody want to waste money on this thing. It will become obsolete by the time you finished assembly. Why can't IKEA just stick to the cheap hokey furniture they are famous for.

For a few bucks extra get a Mapleshades audio rack. I'm hoping to get one in the not to distant future.

Probably has something by now.