The gray text shown in the "Title" and "Tags" edit boxes when creating a new question doesn't follow the usual UI convention for watermark text.
The usual behavior (e.g. of the watermark text of the Browser's own search box, and of other websites) is to clear out the watermark immediately when you set focus to the edit box, and then to restore the text onblur if the edit box is still empty.
On Stack Overflow, the watermark text remains in the box until you start typing. I found myself selecting and deleting the text in the box before starting to type.