Main reason to localize the data is for user experience.
If twitter search slows down, you may have page loads waiting for the
content you need. Also, you will get only 3200 results, or a historical
snapshot of 7 days from a query, so you run the risk of losing data outside.
It all depends on what data you need for how long.
Now, if twitter search data on the fly works good, you basically need to
1. retrieve the data from twitter search (probably json) - I use jQuery so
it would be something like this
2. parse the response result, convert it to proper JSON google
visualizations wants for consumption to create a
3. create a "view" of the data table, specifying the information you want to
display on the graph
4. create the visualization (areaImageChart, annotatedTimeline, etc)
Here is an example from Google where the JSON is hardcoded, but aside from
getting and parsing the data from twitter, this should show you what you