I have the exact same issue/backtrace with Gazebo versions 0.5.2, .0.6.0 and cvs
backtrace:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208354560 (LWP 8485)]
0x0806713f in Model::SetName (this=0x0, name=0x853d388 "Terrain") at Model.cc:270
270 if (this->name != NULL)
(gdb) bt
#0 0x0806713f in Model::SetName (this=0x0, name=0x853d388 "Terrain") at Model.cc:270
#1 0x08064c54 in World::LoadModel (this=0x8532428, node=0x853b6c0, parent=0x0) at World.cc:297
#2 0x08064d90 in World::LoadModel (this=0x8532428, node=0x851e360, parent=0x0) at World.cc:386
#3 0x08065206 in World::Load (this=0x8532428, worldFile=0x8519960) at World.cc:254
#4 0x080633f2 in Init () at main.cc:324
#5 0x0806386c in main (argc=2, argv=0xbfbc26b4) at main.cc:435
