mediafred, the free Adobe Watermark Panel works with Photoshop CS5 and CS6. Details are in this John Nack blog post:
http://blogs.adobe.com/jnack/2010/04/new_watermark_panel_for_photoshop _cs5.html
You'll get a lot of suggestions about actions, scripts, and other techniques for making watermarks in Photoshop, but some of them are old workarounds. Because the Adobe Watermark Panel is rather new and designed as a Photoshop extension, it's also relatively easy and simple to use compared to the older solutions. Because it shows up as a panel in the Photoshop interface, you can save its position as part of your favorite Photoshop workspace preset if you want. If the Adobe Watermark Panel doesn't do exactly what you want, then it would be worth investigating some of the other actions or scripts out there.
If you need to do a large number of images and have Lightroom, I'd recommend doing it there. Watermarking is fully integrated into the Export dialog box in Lightroom, so the time it takes to watermark each image is much less than opening and running a watermark action on every image in Photoshop. In addition, you can save multiple watermark presets, and that can be saved as part of a Lightroom Export preset, so if you have multiple types of export jobs, choosing a different Export preset can also switch to the appropriate watermark for that job.
