Originally Posted by gibboireland
As idone says, there's only one firmware that covers all regions of PS3. The region code (for games, and for Blu-ray movies) is held outside of firmware, and is not changeable.
With regards to Blu-ray movies at 50Hz, note that PS3 HDMI output is either 60Hz, or - if your display supports it - 24Hz. Most (all?) Blu-ray movies are encoded at 24Hz, irrespective of whether they are Region A or B.
If your display doesn't support 24Hz playback, then regardless of your actual region (US/Europe/other) there'll always be some kind of pull-down/up to convert from 24Hz to the display rate (50Hz, or 60Hz).
Hope this helps,
p.s. There's a 'Play videos at 50Hz is available' option in newer PS3 firmware, but I believe that's really to allow for videos exported from PlayTV (which, in Europe, are at 50Hz in Standard Definition) to play without any kind of conversion.