Not surprised by 37 Signal's opinion as they've gotten remote to work because of their passion for creating tools that foster communication.
For me, there are 2 ways to look at Yahoo's decision.
One is they are flat out wrong, but thats OK, because they are making decisions (Steve Jobs spoke of this)! Decisions are what moves companies in directions, good or bad, its better than being frozen and stagnant.
Two, I can attest to the cross pollination of ideas when you're together as a team, sharing lunch, sharing experiences, seeing each other in person, reading each other's body language, etc that just doesn't seem to happen at the same level when you're remote. If I were building a team from the ground up I'd want my team to be hanging out everyday ...the other meta of working together doesn't happen over Skype :). I can't tell you how many solutions were dreamed up on the walk to Starbucks. There is just something there that is hard to replicate with software.