In the meantime, set contenteditable to 'false' instead. Since contenteditable is an enumerated attribute, removing it and setting it to 'false' has the same effect.
Internally, we set attributes to empty string before removal, but IE balks and throws an error because empty string is not a "valid value" for contenteditable (even though it actually is, ironically). Both removeAttribute and removeAttributeNode have no effect on contenteditable in IE6/7, so in order to kill the behavior of contenteditable, it HAS to be set to 'false'. We can provide an attrHook that does this in 1.7, but if removeAttr is used to remove contenteditable and then one tries to get contenteditable, he or she will get undefined in all browsers where contenteditable was actually removed and 'false' in IE6/7 (which is really unavoidable). Either way, I recommend using the other values "true", "false", or "inherit".