When you really put a Business Application into the Cloud you will get several requirements from your customers. I will show you in this post how to address these requirements:
a) Single-Sign-On: Can be achieved using ADFS and WIF
b) ERP-System Integration can be accomblished using Windows Azure AppFabric
Services Bus to connect both.
c) Storing relational data can be done in SQL Azure
d) Security of ASP.NET can be implemented via Single-Sign-On and IPFilters (see codeplex for a sample)
e) Session Management: You need to make sure that session data is persisted to SQL Azure by using the SQL Session Provider for ASP.NET