cpg1.4 will have and advanced user manager where you can search for users. Clicking on a users profile will show a link to the meta album "last comments by this user" (already does so in the current version). Not exactly what you were requesting, but a good start imo.
IP addresses are stored with the comments, but are not searchable in the current user interface. However, you could do so using phpMyAdmin or similar. With dynamic IP addresses being used widely, there's little point in building additional functions based on IP addresses imo anyway.
Joachim