Microsoft opened the doors yesterday, letting business customers start exploring the potential of Office 365; a Software as a Service offering that is intended to compete with Google Apps, Zoho and others. Microsoft is certainly late to the SaaS productivity suite market, but has a huge advantage in terms of brand (and feature) recognition from all those locally installed versions of Microsoft Office. Office 365 lacks the free version that Google Apps offers, and is typically more expensive than Google’s premium version. Microsoft may be betting that this simply doesn’t matter, and that business customers looking to go SaaS will not want to risk any loss of compatibility with Office documents coming from customers, partners, and suppliers. In that case, they’ll probably keep a few power users on full-blown Office, and gradually transition from buying install disks for the rest of the organisation to instead paying an Office 365 subscription. In good times that strategy works for Microsoft, but when every penny is being counted the free or cheaper options from the competition begin to look very compelling. With General Availability of Office 365 currently slated for later this year, Microsoft must be counting on continued strengthening in the economy.