Jason Langridge has just posted about this SIMable unlocking solution. It’s a small chip which fixes to your SIM card which should then let you use your SIM in locked phones.
On certain handsets there’s a degree of SIM-card-snipping and hole-punching, but everything is provided to let you do this. It costs £16.99 plus £2.95 delivery, and currently the only Windows Mobile handsets tested are the Orange SPV M650 and T-Mobile Compact III. If you’ve tried one of these and successfully unlocked your Windows Mobile, let us know. According to the company website it should allow all connections, including 3G data, even on locked phones.