Yes. You can…
Magento doesn’t advertise this or promote this feature, but there is a way to do this as well as mass update other things as well such as images, description and more. The solution is not in the backend admin of Magento either so don’t fool yourself.
Magento has web service API’s you can call using SOAP that is clearly documented with examples. With a few tricks up their sleeve, StudioX, a Tampa Website Design company, has been able to implement this protocol for over 25,000+ items in a Magento shopping cart. They have been even able to handle updating the descriptions dynamically based on reading each products’ respective TEXT file – reading them in, then updating the Magento Details record. Using this web service solution is robust and you don’t have to worry about it timing out like running long scripts through PHPMYADMIN or scripts in the browser. You can update products by category too.
Feel free to contact them to handle mass imports and mass updates behind the scenes.