In a move that signals that Dropbox isn't yet willing to cede the opportunities in enterprise cloud storage to any of its competitors, the company today announced the expansion of Dropbox for Business.

The new product, which was revealed by Dropbox CEO Drew Houston at a press event in San Francisco, is separate and more secure than Dropbox accounts for personal use. The service has already been available to a limited number of businesses since January, but now will be available to all businesses. 

Security is the key feature Dropbox wants to highlight, as many of the 4 million businesses currently using Dropbox weren't previously able to use the application to store highly confidential content or information related to regulated industries. Dropbox's freemium pricing model now allows companies to pay extra for enhanced security features.

Dropbox faces lots of competition from companies like Accellion and Hightail (formerly YouSendIt), which also see gains to be made from focusing on B2B services.

However, Dropbox is perhaps most compared to competitor Box, who's valuation is at about $2 billion, and recently announced it filed for an IPO. Box, which was founded in 2005, has been heavily enterprise-focused since 2007. The company is currently seen as dominating over Dropbox when it comes to security aspects. Though interestingly, both startups say that they each have 97 percent of Fortune 500 companies using their platforms. 

Another highlight of the event: Houston previewed a snazzy new feature designed to help businesses collaborate using Microsoft Office programs. Project Harmony, as it's called, allows two or more people to sync versions of Word, Excel and Power Point docs. They can also use a chat feature, powered by Dropbox, to communicate within an open Word project. Houston said the feature will eventually be compatible with more applications as well.

No word yet on an IPO. With a valuation of $10 billion, Dropbox is one of the highest-valued venture capital-backed companies. Earlier this week Re/Code reported that Dropbox secured a $500 million line of credit, which might indicate that it does not have plans to go public in the immediate future.