The Apple ID is in particular the one used with the iTunes Store and can be created from this page. From now on, it's enough to try your hand in the web browser at iWork for iCloud, ie the office applications Pages (word processor), Numbers (spreadsheet) and Keynote (presentation).
With already Office Online or Google applications, the online office offer was not lacking for those without any Apple device. But they now have even more choices, knowing that iWork for iCloud is currently in beta. Also remember that with iCloud, free storage space is a bit chickish since 1 GB.
The reason for this sudden opening of Apple is not explained. iWork was a paid productivity suite before becoming free in the Mac App Store, and it is now the web applications that open to the greatest number.
Are we going to witness several iCloud surprises with other services that will lose their dependence on the firm's hardware? This seems unlikely a priori.
N.B.: During our tests, the iCloud service was recalcitrant. After a successful first attempt, an error connecting to the server was reported.