Given the viral adoption of SharePoint 2003, and the new architecture of SharePoint 2007, the major ECM vendors are realizing that they can no longer dismiss Microsoft as a company that just generates documents.
As OpenText, Vignette and EMC Documentum look at Sharepoint 2007 and how it is effectively bundled with Office 2007, they have all probably realized that they need to evolve to either embrace Microsoft or find a new way to package their products. The huge marketing budgets that MS is bringing to their ECM offering is an alure, as well as a threat I'm sure.
Russ Stalters on BetterECM suggests that EMC Documentum should extend to the integration to workflow enable Sharepoint documents, which sounds reasonable given the need for strong workflow/BPM to support Sharepoint, although this may be a little shortsighted as MS enhances its document workflow capabilities. Though it obviously plays to Documentum strengths in its raw form.
I'm not surprised that EMC have stepped in here, but I don't believe that they are really trying to sell more Documentum software on its own merits. Documentum provides a single point of integration to hook directly in to a bunch of heavyweight storage boxes, which is probably the reason EMC is most interested in the partnership. Basically, Documentum becomes little more than a 'hub' for mediating storage to a range of EMC devices. But then as the press release states:
As part of this strategic alliance, EMC will introduce a set of new content and archiving products that enable tighter integration between the industry-leading EMC Documentum ECM platform and Microsoft solutions and platform technologies.
"Archiving" is a typical word used when the value of the content is minimal, a company is just looking to store huge amounts of it. If this is how EMC really sees Documentum + Microsoft, this is a perfect play for them in their role of tin merchant.