PlayStation Store Web-Based is Available Now!

[Rockman]

From now on you will be able to access the PlayStation Store directly through your internet browser, simply by going to Sony S.E.N website, and logging in to browse and purchase (free/paid content).

So this makes the PC MediaGo App somewhat useless considering that it was the only way of accessing the store, though, if you own a Sony device (e.g., PSP) and you want to transfer content between PC to it, that may be of use. Or also to have computer media content organised in different categories.

UK: Online Entertainment | Sony Entertainment Network
US: Digital Entertainment | Sony Entertainment Network
All: Available Regions | Sony Entertainment Network
​

Source: Introducing the New Sony Entertainment Network Online Store – PlayStation Blog