At the beginning of each sprint our team will pull in a handful of user stories and then, one by one, write slightly more detailed tasks for them as well as assign specific hours to each task.
Having individual tasks helps us establish our sprint burn-down by having a specific total number of hours up front, as well as make it more feasible to keep track of who's working on what and what all has been completed.
However, I recently read that some mature Agile teams have eliminated the use of writing tasks altogether and head right into their sprints armed only with their user stories as the modularized sources of work for the sprint.
I'm having a hard time seeing how eliminating task planning could still provide an Agile team with small enough units of work so as to keep the sprint organized and transparent. Has anyone here tried or use this approach and if so how do you keep track of exactly who is working on what?