Facebook&39's invite for its event next week.

Facebook is holding an event next week as part of the Web 2.0 Summit taking place in San Francisco, and, according to ZDNet, the topic du jour will be deeper integration between the 500 million user-strong social network and Microsoft's Office Web Apps service.

Facebook and Microsoft already collaborate on a variant of the Web-based Office suite called Docs, which the two companies launched together in late April. However, ZDNet says that this new version will be more closely integrated into Facebook's in-box experience, which is said to be getting an overhaul that builds in Microsoft's services.

Microsoft Office Web Apps contains Web-based versions of Word, Excel, PowerPoint, and OneNote. The suite was launched as a free service for consumers two months after the launch of Docs.com, and included the option for companies to host tailored versions of the tools through Microsoft's Sharepoint.

Based on Facebook's numbers, Docs currently has some 116,000 monthly users, which Microsoft could be looking to grow.

One other area of Facebook where Microsoft's productivity tools could end up is within the recently introduced Groups feature. Facebook launched it with a rather rudimentary word processor, which lets group members collaborate on a hosted document, but something like Word would offer a higher level of functionality, as well as pushing the Groups product closer to something that might entice business users.

Facebook's event takes place Monday at 10 a.m. PT, and CNET will be there to bring you the news.