How to select calendar with "Quick Event" in 10.7 iCal?
You can enter events to specific calendars by holding down the + button

See here the entry from iCal help:


  Add events to a calendar
  
  You can add any kind of event to your iCal calendars. For example, you can add meetings, doctor appointments, and family activities.
  You can’t add events to a calendar you subscribed to.
  
  
  Open iCal
  Click Add (+) at the top of the iCal window or press Command (⌘)-N.
  Events are added automatically to your default calendar.
  If you want to choose a different calendar for the event, hold down the Add button (+), and then choose a calendar.
  To change your default calendar, choose iCal > Preferences, click General, and then select a calendar from the Default Calendar pop-up menu.