How do I create a "quick post" bookmarklet for use with Drupal 7?
Out of the box, Drupal 7 doesn't support form population from the URL. Just like Drupal 6. That's why the Prepopulate module exists. Prepopulate is about 100 LoC, porting it to Drupal 7 is probably the best option. The effort has been started, see issue #935990.