Just run some tests on a widget placed on this site.
Works fine in FF and Safari. Not tested IE yet.
In Chrome it won't display the tweets and as a result, the welcome text to the right moves way up under the slider.
I think this could possibly be a CSS issue, as I am sure there is a better way to set up the div with the text in other than sticking: margin-top: -385px; to get it to sit under the slider. But would this affect the plugin from working correctly?
I grabbed the code for the twitter plugin from the twitter site and it is showing up a validation error also which I'm not sure how to correct.