According to Paul Sullivan of the Chicago Tribune, the Cubs signed their first round pick Andrew Cashner today for $1.53MM. Cashner was the first reliever off the board at #19.
Additionally, the A’s inked first rounder Jemile Weeks, a college second baseman. He gets a $1.91MM bonus.
This site has done a nice job compiling a list of which draft picks have signed and for how much. By my count, 13 of the 30 first rounders have signed.