Ubiquity acts as a web service mashup, integrating a flexible yet powerful “natural language” command line to Firefox. That means you will be able to perform tasks using various web services in one place, quickly, simply and using normal language.

To invoke Ubiquity all you have to do is hit a key combination (Ctrl + Space) and a text field drops down, as you type command suggestions will appear.

Here’s a couple of easy examples to show you what this extension can do.

For example, you can insert a Google map into a new Gmail message (type “map (address)” in the Ubiquity panel); you can look up a topic on Wikipedia in-page without opening a new window or switching tabs; you can select a paragraph of text in a foreign language and translate it in-page or even select a text on a web page and transform it into a PDF document.

See these examples and more on the official site or check out the online tutorial. Version 0.1 is available for download now from Mozilla Labs here.