It is possible, but it depends on what you're planning if it will be necessary. If you're thinking of sending data via USB from a PC to the Arduino to do it, then you can skip a step of course and just get the PC to do it direct to the web.
Typically, you'd be interfacing with other electronics and/or sensors to the Arduino, getting it to interpret and reformat the results in a way that is web-friendly.
What is it you are attempting to do?
Geoff