The CDMA (Sprint) version of the Palm Treo Pro has been unlocked for a while now, meaning you can load custom ROMs and, especially, Windows Mobile 6.5.
Uber-hacker cmnoex has released a version of her hardSPL tool for the GSM version of the phone. A slight word of warning, however, from cmonex herself:
OK right now I don't have time for the final tests (am still without a device) but I suppose it works. let me know if it does.
Grab the unlocker at ppcgeeks. Any brave souls out there willing to give it a go? Let us know (and let cmonex know) in the comments. (And don't forget to donate to your favorite chef!)