The emerging field of cloud computing provides promising opportunities for saving cost and improving efficiency with enterprise applications. However, using cloud computing also implies new application architecture and brings new business models, and it creates security concerns resulting from off-organization hosting. These issues pose several challenges when building new cloud computing applications. Most especially, cloud platforms will lessen the gap between software architecture and IT architecture and will thereby increase the responsibility of software architecture. The result is that software architects must improve their knowledge and experience in this regard. In particular, we expect that future enterprise applications will involve hybrid clouds as a cornerstone in application architecture. This presentation will share software architectural aspects for cloud computing and lessons learned from projects.