Do you want this for individual albums/images or do you want a consolodated list for the whole gallery?
The former can be done by adding a counter to the next_comment() loop. When the counter gets to 10, abort the loop. Right now, the comments are being listed oldest first. This will change in tonight's build to list them most recent first.
There is currently no easy way to get the 10 most recent comments for the whole album. There is code at the end of admin.php which does this. You could copy this code into a custom function and place that custom_function.php file in your theme.
note: the code uses the function fetchComments() which is found in the admin-functions.php script. Your custom function script will have to include admin-functions.php
sbillard, not quite true, we already have functions for the latest comments (no option for a specific album yet, but we probably should add that):
http://www.zenphoto.org/documentation/zenphoto/_template-functions.php.html#functiongetLatestComments
http://www.zenphoto.org/documentation/zenphoto/_template-functions.php.html#functionprintLatestComments