Yes, I frequently use the collage function. I believe (someone will correct me if I'm wrong) that, that is the only way to get more than one pic on a page in Picasa.....
If you use a PC, however, you can use the Windows Live Photo Gallery to print 2, 3 or 4 pics on a page with the print function....
You could edit pics in Picasa and then print with the Windows Live Photo Gallery by saving them into "My Pictures" and then printing from there....
Up to you....

Alison