Hot on the heels of 2.80 being decrypted by Dark_Alex, Sony have released a new firmware, namely 2.81. I haven't checked the features yet but I will be very surprised if there is anything in it worth having. Still, I could be wrong. Personally, anyone on 2.71 or 2.80 I would wait before upgrading as it is unlikely to offer anything new and no games will require it for a long time.
However, I'm sure there are some people out there who will want to upgrade. Download locations below for people interested.
http://www.jp.playstation.com/psp/update/ud_01.html
JAPAN PSP-1000
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
USA PSP-1001
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
AU/NZ PSP-1002
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
UK PSP-1003
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
EU PSP-1004
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
KOREA PSP-1005
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
HONG KONG/SINGAPORE PSP-1006
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
TAIWAN PSP-1007
2006_0907 4726589a847329cb03ac5ffd5096d62e EBOOT.PBP
Will update with feature list when available.