Hi,
From this
Mac OS X 10.5.2 (9C7010)
I can tell you have done the Time Machine and Airport Update.
This takes the OS above the level of the 10.5.2 update (despite it saying it is at 10.5.2)
This in turn means that the Combo Update which would normally be used to update a Reinstall of the app (iChat) and the Support folders will not work.
From what you posted it looks like iChat was making multiple attempts to sort this and each attempt crashed the thread involved (hence the repeats).
Currently it looks like an Archive and Install and then don't let Software Update run the time Machine and Airport Update until you have run the Combo Update and confirmed iChat is working.
5:09 PM Sunday; March 30, 2008