Text entry with the latest nightly build of webkit has a few bugs in it, including text wrapping around the edge of the edge of a text box, which causes text to get broken up in some webpages. However, the worst error is the one found on facebook, where messages or posts will lack spaces.
I can confirm this behaviour with latest nightly. Using Safari Version 4.0.4 (6531.21.10, r55270)
*** This bug has been marked as a duplicate of bug 35457 ***