Greating a PDF file from multiple images

1. Open Photoshop.
2. Go to File->Automate->PDF Presentation. Here is a screenshot of the PDF Presentation menu:
3. Click Browse and select the pictures you want to use in your PDF Presentation.
4. An alternative to step 3 is to have the files already opened up in Photoshop and click on Add Open Files to indicate that you want to include those pictures. 
5. The PDF Presentation menu offers the possibility of choosing some of the picture information to be included in the pdf file. For example, the filename, the title, the picture's description and so on,  can be included by clicking on the appropriate checkbox in the Output Options pane. 
6. Click Save. Name your pdf file and choose a location on the hard drive where you would like the file to be saved. 
7. You're done!

Source : http://b27.cc.trincoll.edu/weblogs/sta/2009/04/photoshop_tip5_creating_a_pdf_file_from_multiple_images.html