You Might try the following solution. It seems to have worked for me.
From CNET MacFixit
Font issues in Snow Leopard casuing iWeb '09 to crash
by Joe Aimonetti
Users of Apple's popular Web site publishing application, iWeb, are experiencing crashes--an issue which appears to be related to a corrupt font in Snow Leopard. When attempting to open and edit pages in iWeb '09, users are met with a crashing application and an error message citing an issue with the sfwordprocessing plug-in.
Users in this Apple Support Discussions forum were stumped, trying several fixes including deleting plist files, repairing permissions, and deleting cache files, all to no avail. In fact, the issue seems to be somewhat random, appearing on some domain files, but not others (running on the same system). New user accounts in Snow Leopard retained the issue, though transferring the iWeb Domain file (username > Library > Applications Support > iWeb) to a system running 10.5.8 Leopard seemed to work fine.
Solution
Apple Support Discussions user "alexdennis" finds a solution after several other users report disabling the Hoefler Text font using Font Book provided a temporary workaround to the problem:
1. Delete the com.apple.iWeb.plist file in Home/Library/Preferences
2. Shut down
3. Boot up holding down the shift key (safe reboot)
4. Shut down again
5. Boot up and run Font Book to resolve duplicated fonts (I've got MS Office 2008 -- you might not need to do this)
6. Shut down and reboot
7. Run iWeb
Many users report that this "total" solution has solved the iWeb issue. ASD user "macuserhelp" reports:
I had disabled the "problem font", and that was a work around that required quite a bit of messing with the site. This however, seems to have fixed the problem, allowing me to use the original font. I had re-enabled the problem font before following your process.
i disabled the hoefler font and didn't do a reboot of any kind, i also fixed the mult font issue in font book then reopened iweb and it worked for me.
10.6.2 update must have done something to our fonts.. booo apple.. i even waited forever before i did the update. the larger apple gets the more problems i am seeing.. hope they get a handle on this stuff.
Thanks for the 'Hoefler' tip. I, too, was experiencing a crash when I tried to open an iWeb site called 'Gazette', which makes use of the Hoefler font. I used 'Font Book' to disable the Hoefler family of fonts. When I relaunched iWeb, my problematic website again opened. I had to choose another font to substitute for Hoefler, so I chose 'Times New Roman' which has a similar look and proportion.
I think you're right about the bug suddenly appearing with the advent of 10.6.2 - hopefully, Apple will work on a fix as soon as possible.
This Apple Discussion forum in invaluable. Apple helps when they can, but when they can't, we help each other.