Yeah dude, set up a custom photoshop action and use the batch render function to spit out all the images.

In the actions panel press record and paste your watermark on. Set the opacity of the water mark in the layers panel and then click stop.

Now go into file>automate>batch and find the action you saved and point the settings to the originals and batch folders and let it go. might take you a few trys to get things right and you may have to click the supress buttons etc.

Once you can do this you can save time batch rendering photos with anything you want (levels, curves, saturation, usm, etc)