As of today (6/13/13), Twitter has provided access to analytics for personal accounts. It still is a fairly rudimentary product that will likely be built out in the coming months, but it is still useful nonetheless.
There are two main sections in the analytics tool. First is a timeline activity dashboard. This dashboard provides data pertaining to posts over the last month and is sortable by ‘best’, meaning the most retweets and favorites, ‘good’, which seems to be a list of tweets that received any sort of engagement, and ‘all’, which is a chronological stream of all of your tweets.
The next part of the tool is the ‘Followers’ section. It provides a basic graph about follower growth over time and info about the demographics of your followers (age, sex, location, interests). Also, in both dashboards there is an option to download the data to a CSV file, if needed.
To me, this seems like a useful tool but not one that offers any great functionality outside of what is already available from other tools on the market like FollowerWonk. This is most likely a play to get individual accounts more involved in the Twitter ad network. With more individuals that are knowledgeable about Twitter advertising and the analytics platform, the more likely they are to pass that knowledge along to their employers and advise them jump on the bandwagon. Trickle up advertising, I guess.