The announcement of a new company, SkyRiver, providing cataloging services to libraries has sparked a number of comments about competing with OCLC and WorldCat. For a number of reasons, I don't think that the result of such a service is necessarily competitive, although I am very glad to see alternatives enter the marketplace, especially for those who do not use OCLC.
To begin with, OCLC is more than an online cataloging service. Admittedly, revenue from cataloging is OCLC's largest income source, so cataloging is not in any way just an incidental function from OCLC's point of view, but cataloging alone is not the point or purpose of OCLC to its users. I see OCLC as a kind of social network where the "beings" are libraries. The value of OCLC is directly related to the population it encompasses, and the social services it can provide based on that population. Shared cataloging copy is one service, but discovery and delivery options probably motivate OCLC members as much or even more than the cataloging effort. This was evident when RLG still existed, as some RLG member libraries who did their cataloging in RLIN also loaded their records into WorldCat in order to participate in the services that OCLC provided.
The value of the catalog copy on OCLC may be second to the value of the holdings information that OCLC maintains. Catalog copy, if that's all you want, can be found in innumerable library catalogs (including the Library of Congress), and some library systems allow you to export or retrieve a full MARC record that you can then add to your own catalog. Catalog copy can also often be found on the retro of the title page in the form of Cataloging in Publication (CIP), although not in MARC format and not as a complete record. But no one else, and no other service, has the combined holdings of some 60,000 libraries, and that's the main thing that OCLC brings to the table. It is only because of these holdings that WorldCat has value to individual searchers and to the libraries who serve them.
The view of OCLC as "the only game in town" for library cataloging ignores the fact that there are libraries who do not participate in OCLC, for a variety of reasons, but who still need to create bibliographic records. These libraries may not be able to afford OCLC's prices for cataloging services, or they may simply not wish to be bound by the standards of that society of libraries. Some libraries, in particular those in corporate settings, are not able to share their holdings publicly, and therefore are not able to participate in the social life of libraries that WorldCat represents.
There are also non-library providers of library catalog records, in particular the vendors who include catalog data with the products they sell to libraries. These vendors need a source of cataloging copy that is unrelated to particular holdings information.
If we can think further down the line, a database of bibliographic records, like that in SkyRiver or biblios.net could become a resource for anyone who needs to work with bibliographic data. This could include anyone on a research project who wants to provide a quality bibliography with a minimum of effort. Although the bibliography will follow citation standards, the basic data is the same as that found in library records.
Another advantage that these and other bibliographic services may provide to us all in the library profession is that they could be a source of data for experimentation. What with RDA looming on the horizon and much talk about updating our data format from MARC to something else, we'll need data to work with. OCLC has historically been slow to change its data, and not without reason: OCLC is integrated into the workflows of tens of thousands of libraries that depend on it for every day functionality. Although the OCLC research division comes up with innovative ideas, the OCLC core functionality is essentially the same as it was two or three decades ago. If we want to experiment with radical change, I for one expect it to come from the sidelines, not the center.