Sony PSP and Mac OS X
Got a Sony PSP on our last visit to Japan and on this page I will put some information about usingt it together with Mac OS X.
PlayStation.jp | PSP Q&A I believe this is the official support home page.
For other languages you can go to http://www.playstation.com/, select your region and language and hopefully find some PSP information.
Firmware updates
Updates for Japanese Sony PSP From here you can domwnload updates. The page is in Japanese, but it's easy Japanese 
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Version 2
Sony has released version 2.0 of the PSP Firmware. It includes a surprisingly useful web browser, support for more audio, picture and video formats and finally support for WPA (wireless encryption).
Version 2.5
With the release of version 2.5 of the PSP Firmware Sony has fixed a lot of Wi-Fi problems it seems. At least my problems disappeared And I can now use all my base stations, WPA etc. without problems.
Version 2.5 must have some sort of bug with photo and music files. For the first time I had a PSP crash on me and the only thing I tried to do was to view some photos in normal jpeg format. I have read that version 2.5 have a very new and different way of checking files and I believe the PSP crash when it find files that it does not like. Older version just said ”unsupported file format” or something like that. I do hope that Sony will fix this promptly.
Sync software
PSPWare from Nullriver Software Sync your PSP with iTunes and iPhoto etc. on Mac OS X. This is what I use now, it's more polished and stable then iPSP. The latest version of PSPWare support the new features that came with PSP Firmware version 2.0.
iPSP Sync your PSP with iTunes and iPhoto etc. on Mac OS X. Early version have some bugs but it shows a lot of promise. Update: New versions got new funktions and new bugs and it keept crashing. I have given up on iPSP.
Connecting a PSP and a Macintosh A good article for Sony PSP owners that use Mac OS X.