A few days ago I needed to file 70+ bugs for the same thing for each locale we support on www.mozilla.com. I then decided to make use of BZAPI(Bugzilla Web Service API), and have created a tiny PHP script to do the job for me. It worked pretty well even the first time I tried it on on http://landfill.bugzilla.org, so I could expect only better performance on bugzilla.mozilla.org.
I will definitely use it in the future, so I created a web interface for it, so the user could choose component, product, version, bugs to block, whiteboard status and such.
If you think my code is bad, or that you can do it better, feel free to fork or send me the patch. Code is at https://github.com/milossh/bugzilla-c3po