It's intentional, but Wizards of the Coast website thas released some previews of DDI. If you dig around - you'll find that the DDI Compendium is actually live . It includes pretty much everything from the new 4th Edition Player's Handbook, all free online from the official source. Seems like they forgot to tell the developers to 'wait'! If the above link is not working, all you need to do is sign up for DDI (currently free, see the link in the upper right on the D&D homepage) and then visit the DDI Compendium page and click "launch". Have fun!
Let us know what you think of the upcoming DDI; will it be worth the $15/month? will it be vaporware, like a much touted previous software bungle (eTools) from WotC?