All litigators who handle disputes for business entities and any business that has already gone through a major piece of litigation understand how expensive, time consuming, to be honest, down-right awful, is the experience of trying to ascertain where all potentially relevant information resides within a company's many computer systems, networks, and individual PCs.
But the world of technology is slowly moving towards data storage somewhere outside the physical locations of many companies and out into the "cloud" (i.e., onto servers maintained by internet service providers or other large companies). Having to search for data, however difficult within your own company (or that of a client), raises yet further difficulties when you need to coordinate with outside vendors and raises all types of questions about control and access to information that your company (or client) may not have thought about.
The articles on e-discovery are legion and many companies have developed consulting services regarding e-discovery. Many lawfirms, including my own, have developed this expertise as well in conjunction with the cases that we litigate for our clients. But the issues with cloud computing are just developing and virtually no law yet exists on the obligations and duties of a litigant to get documents and e-data from sources outside its company that stores the data that you (or your client) only has access to. That may raise all kind of questions, starting with the pre-existing contractual obligations of the cloud provider or the lack thereof.
I have found an excellent series of articles on cloud computing. Rather, than trying to summarize them, let me direct you to the 4th article on the subject of the intersection of e-discovery and cloud-computing. The article is titled Legal Implications of Cloud Computing -- Part Four (E-Discovery and Digital Evidence) by Tanya Forsheit of Informationlawgroup. Also, if you are a lawyer or have an interest in one judge's views on e-discovery in general, you might also want to read the decision Tanya discusses, Lorraine v. Markel Am. Ins. Co., 241 F.R.D. 534 (D. Md. 2007)
The bottom line is that as a company moves to cloud computing and data storage, yet more thinking is required in advance of litigation and once litigation commences or is likely to commence. These are not easy issues nor ones that can be inexpensively dealt with.