2-Way Voice Call Recorder is an application for our HTC Wildfire, Legend, Desire, Desire HD, Desire Z, Hero, Evo, Nexus One or any other Android device, with which we can record the calls from our device. Still not 100% compatible with Android devices, but promises that soon will be.
2-Way Voice Call Recorder support different recording modes, such as Internal Recording, HD Recording, Normal Recording, etc. It also supports voice mailbox, voice message, recording search, sorting, and auto back up to Gmail.
This is a free version (which records up to 60 seconds) with the same functionality with paid version (5.20 euros).
Root permissions are needed to record, so you can install z4root.
PD: You can buy 2-Way Voice Call Recorder from here.