Universal server storage for various small amount of mobile devices related sync data

Introduction:
Nowadays almost every person has at least several devices or computers (mobile or not): phones, smartphones, netbooks, laptops, desktops at home and in offices etc.
But there is still no universal API and centralized storage providing smooth fast and universal syncronization between devices, software etc.

Solution:
It is possible to design universal API for any operating system and programming language that encapsulates the following amount of data and functionality using set of applicable rules and meta-description of real data. Server side most likely will be web-services accessible from any internet-enabled device.

Let's try to put several examples:

Example 1:
Rules:
For every mail application (category)
OR
Microsoft Live client

Data:
Contact list in standard xml based format

Access:
My account only from any device type

Example 2:
Rules:
For every book/periodic reader application (several subcategories of reader devices category)

Data:
Current bookmarks and end of last read page (with symbol precise cause pages can be different on different devices). Per book/periodic

Access:
My account, my family members group, my friends group (if they have such ISBNned book)

And so on for music players (iPod, desktop winamp etc), video stop moment, last web browsing session (urls + cookies + possibly login session info)

That will provide unbelievable transparency through devices rotation in person's life and will require not so big amount of storage cause only links/bookmarks/keys will be stored