From Slackware-current (24-04-2009):

n/bluez-libs-3.36-i486-2.tgz:  Switched back to the BlueZ 3.x series.  As the
  website says, "without support from the userspace these modules are useless."
  Well, it seems as if the userspace support for BlueZ 3.x is still much better
  than the support for 4.x, so we'll move back to these packages (recompiled)
  until the situation changes.  Thanks to Tom Nardi for the detailed report
  concerning the usability of BlueZ 3.x versus BlueZ 4.x.

But GNOME 2.26 has some good support for BlueZ 4.0, so we include it as a replacement
for the Slackware bluez-libs package.