I have the exact same problem: my "save as" window does not display due to the 1024x600 resolution of my netbook. I realize that Adobe clearly states that 1024x768 is the minimum recommended resolution for running Photoshop. However, netbooks are perfect for doing some quick editing while on the road, and this new behavior makes this impossible. With the previous version of Photoshop, the "save as" window was still displayed, and despite the fact that it did not fully fit within the screen, it was still possible to save my images.
My humble request, therefore, is that you please consider reverting to the old behavior of the "save as" dialogue. I'm sure I would not be the only one who would be grateful for that.