Again, thanks to Cool Tools:
GrandCentral lets you save all or parts of a call. Just press the number 4 to turn on and off recording – both parties will hear an announcement notifying callers that call recording has been initiated or stopped. Listen to your recording in your GrandCentral inbox or by phone when you check your voicemail. …You can forward recorded messages just like you do voicemail forwarding.
And it’s free, at least for now.
My postings on related tools: cellphone diary studies, a microphone type device and another web-based service, and another microphone device that works with a phone.