Yes you can. You'll need to setup an action within Photoshop that records the following steps:
Create this action with any particular image. During the creation, simply "Save As" to the desktop as "Foo.jpg" or whatever. It doesn't matter. You can immediately delete this image afterwards.
Then you run a batch process (File/Automate/Batch...).
In the Batch dialogue window:
Select the new action you just created
Select the folder with your source files
Select a destination folder
Next, there are a few rules to follow that are a little counter-intuitive.
Check the following check-boxes in the Batch dialogue window:
Override Action "Open Commands
Suppress File Open Options Dialogue
Suppress Color Profile Warnings
Override Action "Save As" Commands
As an additional suggestion, I create two actions...one for horizontal images and another for vertical images. That way, if I want all the horizontal images to be 640px wide and the vertical images to be 640px tall, I can achieve this.
For horizontal action:
Enter 640 into the "Pixel Dimensions/Width" field of the "Image Size" dialogue window.
For vertical action:
Enter 640 into the "Pixel Dimensions/Vertical" field of the "Image Size" dialogue window.
In both cases, make sure that you have all check-boxes checked in the "Image Size" dialogue window.
Before running the batch process, separate the horizontal images into one folder and the vertical into another. This can be easily done within Bridge.