Cross Platform Serial port communication in Java?

I'm trying to do serial communication with Java. It's hard to believe that there's not some nice, out of the box solution like there is in C#.

I'm looking around the SerialIO website, but it's not clear that there's a free .jar I can download to get the functionality I need. (Is it just for sale? I can't find a link for a .jar download of any sort.)

All I need is read/write over a serial port, and setting a baud rate. Nothing fancier than that.

Edit: I require that it works on 64 bit Windows and Mac OS X. The Java Communications API only has implementations for Linux.