Looks like you have to insert a Page Break, either from the Insert menu or the pink box with the + in it on the Toolbar of the window.
I can't get a Page Layout blank to open, so I've opened one of the Flyers & Posters then deleted all the content. I sometimes need larger poster layouts, so now I have to go to File>Page Setup... then under the Paper Size: popup select "Manage Custom Sizes..." and create the size I want. Then the new Document Inspector (View>Inspector>Document Setup) will recognize it and all of the other custom paper sizes I have created in the past.
If you do this, there is then an option under the Insert menu to add a Page rather than a Page Break as in word processing files.
I added Keyboard Shortcuts for the two Inspectors as Format – Shift-Command F and Document – Shift-Command-D.
Now I can save this layout as a Template and it shows up under File>New...>My Templates.
I'm still trying to figure out how to get an Advanced Find so I can replace special characters like Paragraph returns, Tabs, etc.
I think we are in for a little "re-orinetation" with the new iWork apps.