I've noticed this sending to another N900... if the receiver takes more than about 10 seconds to choose a destination for the file it fails and I get this error. I don't know if this is some sort of timeout or bug, nor whether it is the system bluetooth libraries/APIs or Petrovich.
Everytime I try to send a file via bluetooth it says, "Connection failed to <devicename>"
I've tried this on my MacBook and my Blackberry Bold.