TwitterRSSWithRT plugin by maraboustorkltd allows you to add tweets to your page including any retweets (which are not supported by the json feed provided by twitter.com)
This solution addresses this issue by using your twitter username and the number of status’ you wish to retrieve to contruct the url to the atom feed which is then converted to json using the google api. This json feed is then used in conjunction with a customised version of the code in blogger.js to give you the same output that you would normally have expected but including your retweets.
This code also improves on the standard approach because it automatically allows you to support multiple feeds on the same page because the id of the element that is populated with the tweets is passed to the procedure which retrieves them.
Download and info: http://wordpress.org/extend/plugins/twitterrsswithrt/