you edit the project properties, which is accessed by clicking on the pencil icon available when you rollover the name of your project. From this panel, you can then add the email address of the person you want to share with, and decide what kind of access they can have - Manage, wireframe editing or Preview. If they have a paid account they can edit the wireframe you share, otherwise they can only Preview and add comments

While I see that this works, the email the person you are trying to share the project with only link to http://iplotz.com/ and that is simply the main login screen. There isn't any unique link sent that they can navigate directly to the preview AND have the ability to add comments. I tried simply copying and pasting the preview url that is generated in an email I send manually, but all that link does is allow them to preview, not add comments. That being said, I love your product and have been addicted to it the past couple days. Thanks for all the hard work! :)

Nevermind, I had the person create an account real quick and when they did, they were able to see the project after logging in. Thanks!

we may add the ability to add comments to a preview sent out as a URL, but obviously you won't know who posted a comment on it. I guess if you only sent it to one person you'd know..:-)

As a usability suggestion for iPlotz, I would recommend looking at the way iWork.com handles project permissions (when you publish from Pages to iWork), or how Buzzword handles this. The current UI with the hover of an item in the grid to edit the project properties is not very discoverable- and the drag a persons name to the trash bin or to the email icon is kind of wonky :o)

Why dont use the sharing public url as Mockflow offer...?

COMMENTING DOES NOT WORK FOR UNPAID MEMBERS OF A PROJECT!!!