Attaching Documents on Websites from iPad 3

How can I attach a document when on a website. When I try and attach one from an iPad it only allows me to upload from my Photo's Library.

I would like to upload a Pages, PDF or Word document from Office2 HD??

Is this possible or is this something which Apple will we incorporating in a future update because if this file attachment upload is possible then I feel it will delete the need for a computer altogether.

Thanks