I wrote a text about advanced searching and filtering in Gmail two days ago, now at last published (in Swedish) at http://nyfiken.org/arkiv/191.
In my text I summarize Googles search options. WP kept saving drafts of my text while I was writing it, but when I was almost ready the autosaving hung. When I tried to publish I was sent to a public page on my blog stating that I was looking for something that could not be found. I tried over and over again, and have kept trying for two days now.
My final approach was to keep my draft in a text editor, pasting the first paragraph into the WP editor (write post page), adding title, tags and categories once again, pressing Save and keep editing, and when this worked as expected repeating with one more paragraph.
This way I was able to find the exact combination of characters that locked up the system, making it impossible to save or publish, and making WP hang when trying to autosave the draft. A post containing 'bcc:' will not save. Inserting <wbr></wbr> between all letters of the phrase finally solved the problem.
I have no idea if the bug is in WP core or in some plugin I am using. I still run WP 2.3.1, would have upgraded if this bug had not kept me busy, the theme is a modified Genki theme.
AddThis Social Bookmarking Widget (drop-down)
Dagon Design Sitemap Generator
Executable PHP widget
Get Recent Comments
Google Adsense widget
Google Ad Wrap
Google XML Sitemaps
Simple Tags (1.2.4 -- other plugins are latest version)
technorati Feed Widget
Top Posts By Category
WordPress Database Backup
WP-ContactForm: Akismet Edition (not working)
I may not be reading responses to this, but bughunters are welcome to contact me if you need more details.