The whole idea is that you interact with Web things through a command line in the browser that is close to natural language; it's all a bit like this post about the world's favourite command line. But at the moment it's not particularly useful for anything. Leave aside the fact that 'email firstname.lastname@example.org' creates an e-mail message with a blank to: field and the string 'email@example.com' in the message body (yes, they actually did that).
But it's missing something crucial. |. If you're familiar with command lines in general, you'll recognise it - it's the character commonly called a pipe. If you're not, it's called a pipe because, on a command line interface, it's normally used to "pipe" the output of whatever command was issued before it into the input of the command that comes after it. For example, on a unix/linux machine, you could
wget http://yorksranter.wordpress.com/ | grep Worstall | mail 'firstname.lastname@example.org'and dear old Firstname Lastname gets a e-mail containing a list of the occurrences of the word Worstall on the front page of my weblog. We sent a command (wget) with an argument (my URL), and then we sent the output to a second command (grep), with a search string (Worstall), and then we sent the result of that to yet a third command (mail).
We could keep chaining them together; we could use logical operators as well, which means that the Unix shell is a programming language in its own right. Alternatively, in some command lines and every programming language I've ever heard of you can wrap a command in (brackets) and it's like putting its output there. This is the whole point of a command line; it's the main reason why anyone would bother with one in this day and age. As far as I can work out from a brief perusal of the voluminous hype and much scantier documentation, Ubiquity is meant to help you do multiple tasks on the Web efficiently. But without either a | or else a (), it's no use at all.