how do I share photos on the web with iPhoto / iCloud?
iCloud is not a replacement for MobileMe--those great-looking photo albums are a thing of the past.

Photostream shares photos between Macs, iPads and iPhones, automatically and pretty instantaneously — unless of course you turn it off -- in a separate album from the device's camera roll. 

Apple no longer provides a way to share photos on the web. Mores the pity. 

Edit: iOS 6 offers Shared Photo Streams on iCloud.com. 


  Shared Photo Streams allow you to post and share photos to a Photo
  Stream album hosted by iCloud. The photos stored there don't count
  against your iCloud storage allotment, and will work over Wi-Fi and
  cellular data. You're able to share photos with fellow iOS users as
  well as by creating an iCloud.com Shared Photo Stream album for
  non-iOS users.


See the rest of the How-To on CNET.