Actually it really depends on the Palm.... some have TTL Serial comunication ports and othes have the standar RS232. The conversion is made at the docking when they have a TTL serial port. Either way if ou connect it to the PIC you are going to have a good connection.
I have connected a lot of PIC straight to the serial port on the PC, without the need of a MAX232, as long as you keep the cable short and use some resitatnce to limit the current. Comunicatons are stable but I woldn't recommend that unless you have the TTL serial port in the palm. A TTl serial port is prone to noise.
I have used NSBASIC Palm to program palms and have been able to comunicate to a PC easly...... I bet a PIC would not be any different.
Good Luck
Ivan