The Answer is "NO" however, it is good practice to always use semicolons.
If you are a PHP , C++, C# and a few others, you know a thing or two about using semicolons so it will be natural to you.
Advocates of not using semicolons whines about two much typing, redundancy, file size and so on. Honestly, i do not consider them as problems.
The only answer i would have for them is this:
When I switched from Javascript to C++, C# , PHP I do not have to worry about a thing because I always use semicolons.
Also It appears that some of the Javascript minifiers out there do not do a good job if the semicolons are not used.
Related Article
http://mislav.uniqpath.com/2010/05/semicolons/