yep, looks like it. if you check for example: http://posterous.com/explore http://posterous.com/explore You can see all pretty unique titles without a number a

yep, looks like it. if you check for example: http://posterous.com/explore http://posterous.com/explore You can see all pretty unique titles without a number appended and then a post titled "Tetris" gets "/tetris-194" Even if you post something without a title it just gets an ID assigned which is (this is a guess tho) the unique ID in their database of all blogs.