Can Visualforce pages exposed in the Salesforce1 mobile application be opened offline, and if so is there any offline storage available, such as HTML 5 local storage?
Among my contacts at SFDC, this is a "hot" feature request. Somehow here in Germany a lot of people come up with that requirement. At sf1 world tour in London, I attended the breakout session "Salesforce1 Platform Roadmap" and it was said, they are working on that, but at the moment, there is no offline support.
So I would say: no offline support for now. I will verify this on the sf1 world tour in Munich on July 3rd.
first , sorry for my english :s unfortunatly it is a foreign language for me (also I've answered with my Iphone which has a french keyboard).
Second, you can create any visualforce page , declaring a "manifest" (which list all the files/pages/images you want to be able to load offline) directly in the visualforce page (in the tag and host the visualforce page in a Site.com website , (or on HEROKU, this is what I do ) . and then , load this page within Salesforce1, Offline. I'm currently in a process of validating my Salesforce1 offline package with the Salesforce security review (free app) , but it's taking quite long.
Also, to serve an offline VF, using a weblink or and integration in a page layout seems to be the only way. It seems that lightning is also supporting this feature natively (I think I saw in the manual that the tag name is AppCache).
I'll be happy to share code or to help if you want