Having been kept apart like Romeo and Juliet, Microsoft Office is finally getting to meet the browser. Google made the introductions.

The next version of Office, a rev called Office 14, will include lightweight versions of Word, Excel, PowerPoint and OneNote that work on the Microsoft Internet Explorer, Apple Safari and open source Firefox browsers.

Microsoft said so at its Professional Developers Conference Tuesday morning and gave a brief demo calling them “Office Web Applications.” The documents look just like Office documents down to the watermark.

When Office 14 can be depended on to finally get to market is anybody’s guess – it could be 18 months from now – but there is supposed to be a closely held technology preview later this year and talk of a beta early next year.

The webified apps, a catch-up to Google Apps, Zoho and others, are supposed to let users view, edit and collaborate through the browser and synch up (complements of REST) whether on a PC, the web or the phone.

They are expected to have more functionality than Google’s Apps but not an offline mode, protecting Microsoft’s full desktop interests. Apparently Microsoft has been showing the stuff to large account under NDA to ward incursions from Google.

Consumers will get delivery through Office Live, which is currently either ad- or subscription-based and can potentially provide storage. Business customers will get access either as a fee-based hosted subscription or as part of their existing volume licenses via SharePoint.

Office is now Microsoft’s biggest money maker, ahead of even Windows. Last year, which ended in June, it generated $18.9 billion in revenues and kicked in $12.4 billion in earnings.