OSX builds not working

I've tried to get the various builds to work on my Mac as they have come out but they always crash. Am I missing something?

Model: Macmini2,1, BootROM MM21.009A.B00, 2 processors, Intel Core 2 Duo, 1.83 GHz, 2 GB
Graphics: kHW_IntelGMA950Item, GMA 950, spdisplays_builtin, spdisplays_integrated_vram

Process: SoulseekQt [194]
Path: /Volumes/SoulseekQt/SoulseekQt.app/Contents/MacOS/SoulseekQt
Identifier: com.yourcompany.SoulseekQt
Version: ??? (???)
Code Type: X86 (Native)
Parent Process: launchd [124]

Interval Since Last Report: 382 sec
Crashes Since Last Report: 1
Per-App Interval Since Last Report: 6 sec
Per-App Crashes Since Last Report: 1

Date/Time: 2011-07-21 00:11:57.640 -0400
OS Version: Mac OS X 10.5.8 (9L31a)
Report Version: 6
Anonymous UUID: AB3DB4FB-1883-42BD-8447-AE484B56EEC0

Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread: 0

Dyld Error Message:
Symbol not found: __ZNSo9_M_insertIyEERSoT_
Referenced from: /Volumes/SoulseekQt/SoulseekQt.app/Contents/MacOS/SoulseekQt
Expected in: /usr/lib/libstdc++.6.dylib

I'm not sure what's happening here. It looks like it's missing a symbol in /usr/lib/libstdc++.6.dylib. Do you have that file on your system? I don't know a lot about Macs, it might be something that gets installed as part of another package.

edit: There's a discussion here that may relate to the problem you're having. If I understand it correctly, Qt apps are meant to run on OSX 10.6 and up?