In case you missed it, using a kernel hack, you can downgrade your 2.71 version firmware to 1.50.
Read more about it at:
http://forums.psphacks.net/index.php/topic,18038.0.html
And grab the full set of files, including 1.50 ROM related from:
Download
This is a great news for people who have upgraded, but wants to play home brew games and cannot do so with 2.71 firmware. As most you know already, v.1.50 firmware allows many home brew