So far my clients and I have been very impressed with ZenFolio and I'll be upgrading to the Premium account this week. Love it! 

One thing that's lacking, however is the option to see and order a photo in B&W or sepia. Please, please (and very soon hopefully) add an option to see an image in B&W (it doesn't have to be an amazing representation) and add the option to order it converted. Perhaps as an add-on? Or as a drop down menu for the print on the check out page.     

I know that this is being dicussed by the development team so we will see what happens

I agree, this would be great.  I have had a few clients ask me about this.  Obviously I can go convert the images and upload them, but it would be much easier if they could do it themselves!