I have been having trouble with various Ajax sites. For example, I go to my bookmarks on del.icio.us, click edit on a bookmark and add a tag with the in place editor that appears. When I click "Save", the tag seems to be there but it in fact isn't, (which I can see by bringing up my tags in another tab or refreshing). If I go to full screen edit it works fine (but is also probably not Ajax).

I have had flaky behavior with the Digg button on Digg and the comments section on Digg. Unfortunately, I haven't been able to repeat those problems reliably.

This is with OmniWeb 5.5 beta 4 running under Mac OS 10.4.7