BTW-I'd like to step back from the rules debate for a moment, and talk about the play concerns that (I think) lie at the root of this issue. Darklone is concerned that 'taking 20 with traps is not fun'. I think that the concern of many DM's is that if taking 20 on Search checks is allowed, the players of Rogues will take 20 on every 5' square and always find every trap, secret door, and hidden treasure that has a reasonable Search DC.
IME, this just isn't the case. Just for an example-I have a copy of WOTC's Sunless Citadel adventure sitting here. Counting squares, and taking walls into account where they exist, I reckon that there are ~250 squares that could be searched between the first encounter and the second. If the party rogue insists on taking 20 to Search every square before the party enters/passes it, he definitely will find every trap and every secret door in this area. This will take two minutes per square, or approximately eight hours ...
Nobody is going to do this. It's an unusually cautious party/Rogue that insists on even making one Search check on each square as they pass. In that adventure, one of the objectives is to try to rescue some missing adventurers. Even presuming they're not in any danger, one has to factor in their lifespans to the equation. They're not elves, and they'll be dead of old age long before a group that insists on constant Take 20 Search checks finds them.
What you'll find is that most parties (a) have members with decent Search check numbers split up most rooms for a cursory (one-roll) once-over, and (b) have rogues take 20 to Search specifically obvious sites for traps/secrets. When your locked treasure chests are trapped, the rogue will spend two minutes examining it and conclude that it's definitely trapped. So what? This is 'not fun' only if your idea of 'fun' is to never let characters demonstrate their superiority at their areas of expertise. A party with a cleric will handle undead with relative ease [barring the cleric being a dwarf with an 8 Charisma-voice of experience], a party with a bard will glide through social situations, and a party with a rogue will rarely have big problems with traps. Deal.