But it's not in beta (yet). Here's a bit of info from my Office 2010 Special Report.

There's not much to say yet about Office Mobile 2010, but it will appear in early 2010 on Windows Mobile-based smart phones and will further Microsoft's promise to make Office functionality available beyond the PC desktop. Office Mobile 2010 will include new versions of Word Mobile, Excel Mobile, PowerPoint Mobile, OneNote Mobile, as well as a SharePoint client that will allow you to access SharePoint-based Office documents.