Note: This page is geared towards upgrading from v0.2.9. Please make sure you view all the version notes for versions you may be skipping (ie. from 0.2.5 → 0.2.9).
Please make sure you review the 0.3.0 changelog before upgrading.
Due to changes in the javascript on the cart page (specifically the addition of the JSON object), the javascript calls added by FoxyCart to your cart templates are now inserted immediately after the closing </title> tag. Without the title tag, the javascript will not load, making your cart less than functional.
In an effort to clean the checkout HTML a little, some of the ID tags on li tags have been removed in the shipping section. Odds are that this won't affect you, but it's worth noting.
If you're using multiship, you'll need to play around with Firebug a little to familiarize yourself with the new elements.