Power of semi-colon in javascript

I have been scripting since 2years from now and when i saw this link:

http://robertnyman.com/2008/10/16/beware-of-javascript-semicolon-insertion/

I thought there is some thing new, infact a lot more about javascript that i should know. Please go thru this link to have more understanding of semicolon.

Also while using jquery if you use the jquery file as,

<script src="js/jquery-1.2.6.min.js" type="text/javascript" /> //bad

The correct usage would be

<script src="js/jquery-1.2.6.min.js" type="text/javascript" ></script> //correct usage