As noted on the development blog, Wordpress just switched development version numbers from 1.3 to 1.5. There are rumors going around why they did that. The main reason:
Something went terribly wrong.
Word has it that the Wordpress core development team has been tapping into the very fabrique of cosmos itself lately, with some very strange results.
Don’t rely on my word, I got proof of this. In the last Wordpress newsletter, the founder of Wordpress stated it in clear words: “It blows my mind”.