I'm using WordPress 3.3.2 multisite and Multilingual Press to manage two sites apart from the root: /en/ (English) and /fr/ (French).
The problem I am having is very specific:
The language switcher widget no longer works properly when a page template contains any usage of the query_posts() function to fetch posts. Instead of pointing to the equivalent page in the other language, the link on that page will point to the root page of the other language. Removing query_posts() from the template will restore the desired functionality of the language switcher widget.
Is this a bug with the plugin, or am I missing something?