You can use Photo Batch Watermarker to...

Add digital watermark to your images on Flickr to protect your photos
Replace your Flickr photos with their watermarked copies
Change the sizes of a batch of photos at the same time
Rotate a batch of pictures
Add text, logo, comments to pictures and Flickr photos
Rename a large number of pictures with just a few clicks
Create watermark templates on your own

Key Features:
Import pictures and photos from your Flickr account or from your computer
Add text or image watermark to a batch of pictures
A set of professional presets for text watermarks
The opportunity to edit all attributes of watermark (transparency, fonts, backgrounds, etc)
User-friendly interface
What is Photo Batch Watermarker ?
Photo Batch Watermarker is a batch watermarker software for Microsoft Windows ® that can make your image protection fast, easy, and comfortable.

Flickr users get the most advantage using the software, because they have an opportunity to import their photos directly from Flickr, to add the watermarks and to upload them back to Flickr!
With all this going on, the filenames, descriptions, tags and comments (attached to your photos) will be saved.