I have found PanoDroid(http://www.frank-durr.de/panodroid.html) that is a library to download Flickr images and transform them into a panorama image.
I had to change a lot of things in the library and just use her kernel, but the result was very good. Panodroid do a great job with big images.
But unfortunatelly Panodroid don't implement Hotspots. I will have to add this feature into the library.
--EDIT--
Frank Durr had transformed PanoDroid into a open source project.
Here is the link to his explanations: http://www.frank-durr.de/?p=26
And here is the link for the OpenPanoDroid: https://github.com/duerrfk/OpenPanodroid