I think I've narrowed it down to a driver that the reprap host software installs, here is a log of it installing, I've found a couple of the files it has installed and moved them to trash but it hasn't helped
2/7/11 6:19:12 PM Installer[2275] @(#)PROGRAM:Install PROJECT:Install-594.1
2/7/11 6:19:12 PM Installer[2275] @(#)PROGRAM:Installer PROJECT:Installer-430.1
2/7/11 6:19:12 PM Installer[2275] Hardware: MacBookPro6,2 @ 2.40 GHz (x 4), 4096 MB RAM
2/7/11 6:19:12 PM Installer[2275] Running OS Build: Mac OS X 10.6.6 (10J567)
2/7/11 6:19:12 PM Installer[2275] RepRap Installation Log
2/7/11 6:19:12 PM Installer[2275] Opened from: /Applications/reprap-mendel-20100806/RepRap Drivers.mpkg
2/7/11 6:19:18 PM Installer[2275] <ZeroSliderSplitView: 0x10023f390>: the delegate <TargetSelectPage: 0x100467c50> was sent -splitView:resizeSubviewsWithOldSize: and left the subview frames in an inconsistent state:
2/7/11 6:19:18 PM Installer[2275] Split view bounds: {{0, 0}, {402, 104}}
2/7/11 6:19:18 PM Installer[2275] Subview frame: {{0, 0}, {0, 32}}
2/7/11 6:19:18 PM Installer[2275] Subview frame: {{0, 0}, {402, 104}}
2/7/11 6:19:18 PM Installer[2275] The outer edges of the subview frames are supposed to line up with the split view's bounds' edges. NSSplitView is working around the problem, perhaps at the cost of more redrawing. (This message is only logged once per NSSplitView.)
2/7/11 6:19:48 PM Installer[2275] ================================================================================
2/7/11 6:19:48 PM Installer[2275] User picked Standard Install
2/7/11 6:19:48 PM Installer[2275] Choices selected for installation:
2/7/11 6:19:48 PM Installer[2275] Upgrade: "RepRap"
2/7/11 6:19:48 PM Installer[2275] Upgrade: "FTDIUSBSerialDriver_10_6"
2/7/11 6:19:48 PM Installer[2275] Upgrade: "librxtxSerial"
2/7/11 6:19:48 PM Installer[2275] Upgrade: "RXTXcomm"
2/7/11 6:19:48 PM Installer[2275] ================================================================================
2/7/11 6:19:49 PM Installer[2275] Configuring volume "Macintosh HD"
2/7/11 6:19:49 PM Installer[2275] Free space on "Macintosh HD": 83.93 GB (83930181632 bytes).
2/7/11 6:19:49 PM Installer[2275] Create temporary directory "/var/folders/1t/1tBEp4r1GkWyzZF8sRF54++++TI/-Tmp-//Install.22752mYgm3"
2/7/11 6:19:49 PM Installer[2275] IFPKInstallElement (5 packages)
2/7/11 6:19:49 PM installd[2283] PackageKit: ----- Begin install -----
2/7/11 6:20:05 PM com.apple.kextd[10] Cache file /System/Library/Caches/com.apple.kext.caches/Directories//System/Library/Extensions/IOKitPersonalities_i386.ioplist.gz is out of date; not using.
2/7/11 6:20:05 PM com.apple.kextd[10] Rescanning kernel extensions.
2/7/11 6:20:05 PM com.apple.kextd[10] Cache file /System/Library/Caches/com.apple.kext.caches/Directories//System/Library/Extensions/IOKitPersonalities_i386.ioplist.gz is out of date; not using.
2/7/11 6:20:51 PM kernel FTDIUSBSerialDriver: 0 4036001 start - ok
2/7/11 6:20:53 PM com.apple.kextcache[2291] JMicronATA.kext does not declare a kernel dependency; using com.apple.kernel.6.0.
2/7/11 6:21:00 PM com.apple.kextcache[2291] Created mkext archive //System/Library/Caches/com.apple.kext.caches/Startup/Extensions.mkext.
2/7/11 6:21:00 PM com.apple.kextcache[2289] /: no supported helper partitions to update.
2/7/11 6:21:00 PM installd[2283] Installed "RepRap" ()
2/7/11 6:21:00 PM installd[2283] PackageKit: ----- End install -----
2/7/11 6:21:01 PM Installer[2275] Running install actions
2/7/11 6:21:01 PM Installer[2275] Removing temporary directory "/var/folders/1t/1tBEp4r1GkWyzZF8sRF54++++TI/-Tmp-//Install.22752mYgm3"
2/7/11 6:21:01 PM Installer[2275] Finalize disk "Macintosh HD"
2/7/11 6:21:01 PM Installer[2275] Notifying system of updated components
2/7/11 6:21:02 PM Installer[2275]
2/7/11 6:21:02 PM Installer[2275] **** Summary Information ****
2/7/11 6:21:02 PM Installer[2275] Operation Elapsed time
2/7/11 6:21:02 PM Installer[2275] -----------------------------
2/7/11 6:21:02 PM Installer[2275] disk 0.01 seconds
2/7/11 6:21:02 PM Installer[2275] script 0.00 seconds
2/7/11 6:21:02 PM Installer[2275] zero 0.01 seconds
2/7/11 6:21:02 PM Installer[2275] install 72.10 seconds
2/7/11 6:21:02 PM Installer[2275] -total- 72.12 seconds
2/7/11 6:21:02 PM Installer[2275]
2/7/11 6:21:02 PM Installer[2275] IFDInstallController 4388F0 state = 5
2/7/11 6:21:02 PM Installer[2275] Displaying 'Install Succeeded' UI.