To get the tweets for any user in JSON format you can visit http://api.twitter.com/1/statuses/user_timeline/username.json?callback=?
Where username is the twitter username.
Make sure that you first have jquery included in your page like this:
Then add this script to pull the last tweet for a username:
Replace techhike with the twitter username that you are interested in.
Next add this markup to your page:
This will act as a container for your last tweet.