That sound you just heard was the collective sigh of all the marketing automation technology vendors that had hoped Salesforce.com would acquire them. Instead, today Salesforce.com announced its purchase of technology vendor ExactTarget for approximately $2.5 billion. Under the terms of the agreement, Salesforce.com will buy all outstanding shares of ExactTarget for $33.75 per share.

No crystal ball was needed to predict that Salesforce.com would purchase a marketing automation vendor at some point. While the company played the role of vendor-agnostic, supporting a number of marketing automation solutions through its AppExchange, all bets were off once rival Oracle purchased marketing automation platform vendor Eloqua in December 2012.

So, what does Salesforce.com gain from its ExactTarget acquisition? At its heart, ExactTarget is a provider of email marketing solutions. But you won’t find email marketing mentioned in Salesforce.com’s press release announcing the acquisition. No one wants to admit that there’s still a place for email marketing in a demand creation tactics portfolio, particularly for driving transactional sales. But did Salesforce.com need to spend $2.5 billion to expand its email marketing capabilities?

Instead, the terms “digital marketing” and “marketing automation” are bandied about in the press release. “Marketing automation” refers to Pardot, which ExactTarget purchased in October 2012. Interestingly, there’s no mention of Pardot in the Salesforce.com press release, although Salesforce.com CEO Marc Benioff did Tweet that Pardot was his “new favorite marketing application.”

The Pardot functionality will be the most interesting aspect of the acquisitions to organizations that support longer buying cycles, and a key to enabling Salesforce.com to deliver on the value proposition it claims for its Marketing Cloud.