title: Safari 5 vs. Safari 4 : Are there any compatibility differences?
body: <p>I recently obtained a Mac so I could test our sites on Safari and Firefox for Mac OS.</p>
  
  <p>Now that Safari 5 is out, I'm not sure what I should do about upgrading.  I presume what works on Safari 5 works on Safari 4, but I can't be sure, and vice versa. So, I don't know if I should upgrade and test on Safari 5 or keep on with Safari 4.</p>
  
  <p>Are there any major differences between these two version in terms of CSS (2.1) handling or JavaScript? When do you think the majority of people will have Safari 5 instead of 4?</p>
  
  <p>All thoughts appreciated.</p>