Just purchased, and also having this problem.
Clicking 'Add to bookmarks' brings me to a page that confirms the page title and URL, but clicking on 'DONE' does nothing (other than a confirmation flash of the button). It always shows the DONE button on the keyboard and doesn't add the bookmark. I can exit out via the 'MENU' button.
Also, clicking on 'Show Bookmarks'....it only brings me to a blank screen which has some lines and an 'Edit' button. Clicking on 'Edit' changes the button to 'Done', but it doesn't do anything. Trying to open one of the lines to add the info doesn't work. I can only exit this screen via exiting PreBrowser by pushing the Home button.
Lastly, my area to swipe for using SBSettings doesn't work anymore, as well as the activation method for initializing ProSwitcher (which is set up to use the HOLD option on the Status Bar).
Also don't see a way to close tabs, just the button at the bottom to switch between them.
It looks like there is some integration with the built in Safari app, as PreBrowser seems to know my logins on web forums....
It would be awesome if I could get the bookmarks to work, or if it could automagically pull up my existing Safari bookmarks (as I use MobileMe to sync bookmarks across my MacBookPro/iPhone).
And, maybe it's placebo effect, not sure, but PreBrowser does seem faster at loading a few of the websites I chose (MR Forums, for example).