My husband's surgeon, Dr. Linda Liau, does them at UCLA. She was featured on 60 minutes or another show performing one on a world class pianist. It was an option that they were considering for my husband because of the location of the tumor in the speech area.
here is her bio
http://neurosurg.ucla.edu/Faculty/Liau/Faculty_Liau.html
Basically, what happened is we went for a consult, as another hospital said his tumor was inoperable. They did MRI scans, Functional MRI scans, mapped the brain - there was a tumor board that meets weekly that unanimously agreed that he should have surgery.
The surgery went well and they got everythign that they could see.
There is a brain conference that is free at UCLA this weekend, where they go over options, treatments, and clinical trials. I suggest if you want another opinion, to call them.
As for biopsy or surgery, I lean toward surgery to get it out - but this is a decision between you and your team of doctors.
Good luck, and God Bless
Gayle C - wife of John C, GBM warrior since Sept 06 - still having great scans, thank the Lord.