Cloud computing promises incredible benefits for companies looking for inexpensive and scalable computing solutions without the need (or the costs or employees) to do it all themselves. However, as foreshadowed in the InfoLawGroup's "Legal Implications of Cloud Computing" series (see Part One, Part Two and Part Three) data security, privacy and legal compliance issues are beginning to cause great concern. Stories like this highlight these concerns. High profile information security snafus (fairly or unfairly) have also stoked the fire: Rackspace power outage, Amazon denial of service attack, and the Sidekick Data Loss. Data leakage is maybe problematic as well based on Cloud architecture. In fact, the InfoLawGroup has encountered some companies that are taking a pass on cloud computing ("v. 1.0") because of regulatory, privacy and security concerns. Do these compliance concerns threaten the Cloud computing model or potentially reduce the cost benefits it promises?