Samsung, and nearly every Android OEM, has a poor track record for timely Android updates in the US. The Galaxy S III Jelly Bean update started rolling out to those outside the US already, but the US is always delayed due to our wireless carrier system. According to BGR, Samsung issued a press release that US owners will see the update from their carrier in "the coming months". Wow, can they get any more vague?
I decided that the coming months was too long so I went ahead and rooted by GSIII and put Jelly Bean on it a couple of days ago. Keep in mind that doing this will void the warranty of your device, but since I have used the warranty once in over 100 smartphone purchases I really don't care about that. I was primarily driven to get Jelly Bean on my GSIII because I think the GSIII is one of the best Android devices available, in terms of hardware, and can't stand Samsung S Voice while I find Google Now on my Galaxy Nexus to be fantastic. I wanted Google Now now so that drove me to perform the steps to install Jelly Bean. It really isn't that difficult and there are some excellent, detailed guides available on the XDA Developers site.
In addition to Google Now, the Jelly Bean update includes the following:
These enhancements and updates were enough to push me to install the Frosty Jelly Bean ROM and so far I am quite happy with it. I may go back to the stock Jelly Bean update when it arrives in "the coming months". BTW, T-Mobile Tweeted that the Galaxy S III is their all-time best selling device.