I'm thinking about implementing a custom ViewState storage, most likely - in a database, like it is described in this article. It may do several good things: make pages more lightweight, together with Cross Page Post Back allow for implementing Post/Redirect/Get (PRG) pattern in ASP.NET application, maybe even allow for some custom history / breadcrumb solutions for application / page lifecycle...
However, I have one concern: having multiple browser's Tabs or windows. When you work in Internet Explorer, you can open a new tab and have it to work with the same ASP.NET application, it will share session. With Firefox, you can even open a new window and it will share session. Now, if we use links (GET operation) to go from page to page, GUID is not passed between pages, and custom history / breadcrumb cannot work correctly with multiple Tabs. The only (ugly) solution I see is to modify every link on ASP.NET page to include GUID.
