Yes, I was waiting to see a Basecamp alternative written in PHP :D
Same here. Imagine the horror of the 2 top dudes at Basecamp.
There's plenty of free Basecamp alternatives out there, but since they don't even come close to providing the same stability and polish none of them have a chance at unseating the original in the eyes of its core audience.
Their customers don't give a shit about some open source alternative.