Test: 
When page loads, start tabbing, and then tab some more... (10 - 15 tabs)

Results:
- Firefox 2 & 3: results mostly as expected. after 1 cycle, the tab back into the content 
  selects the body and returns an undefined target, but still triggers a keyup event

- IE7 & 6: results not as expected. the initial tab to the "text" input fires the a event, 
  but after 1 cycle, the next tab to "text" input does not trigger a keyup event

- Safari 2 3: results as expected

- Opera 9: results mostly as expected. unlike all other browsers, tabbing does not cycle through 
  the browser controls, only through the elements on the page