Catalyst Office is a Web-based small business collaboration suite. It appears to have a solid e-mail, IM, calendar, and to-do application, and it's also supposed to sync with Outlook. It also handles the check-in and check-out of business documents. Unlike other online suites, like Zoho and ThinkFree, Catalyst does not offer online editing of work documents. Rather, its file management system checks out documents to users as they need them and fires up a local editor (Word, Excel, or presumably other desktop productivity apps like those in the OpenOffice suite). The system stores all work documents on its own servers, though, and takes charge of backups and versioning.
The Catalyst architecture means that users get the snappy performance and tools they're accustomed to. But it also means they have to remember to "check in" their files when they are done working with them, and that collaboration on documents is asynchronous, not real-time. The service biils by the month for document storage space used. See also Joyent (review)