I asked in my company about using SQL Azure. Our issue is that most of our databases use HIPPA (health) data that has privacy issues. All of our production databases have to be in our datacenter by contract.
For larger hospital customers we fill their security questionaires on how we handle patient data.
If we had to put on there that our patient data in on the "SQL Azure Cloud" it would likely cause us to lose customers.
I think that any databse dealing with anything sensitive (credit card data, patient data, etc) will not be able to move to SQL Azure.
Most companies have sensitve data in some of their databases, therefore they are going to already maintain SQL Server in-house.
And if you are just considering SQL Azure for other applications, why add the cost of SQL Azure?
Just put the extra databases on the existing SQL Servers that you have to keep in-house anyway.
Our attitude is that our non-sensitive data goes on the same SQL Servers as our sensitive data.
We have already paid for the SQL Server licensing and the SAN infrastructure. Those would not be going away, so there would be no cost savings.
We would just be adding a cost that we don't need.
There is no reason to do SQL Azure also since we HAVE to maintain the in-house secure servers.