The old union website was launched 3 years ago, and money for the revamp came from advertising revenue generated by the site. It isn't really a 'new' site, but an upgrade of the old one, which should provide a better experience for clubs & societies (who are the biggest users of the online payments system). The content is also being reworked to provide better advice and more resources for the academic rep network.
All of the portacabins are now gone and Prince's Gardens is returning to its former peaceful self.
Not to mention the many other tricks, including several which are extremely dodgy with regard to employment law, that Imperial are pulling at the moment. Particularly with support staff in FoE departments, where various people seem to be making the procedures up as they go along, with the tacit support of HR.