No. Polyphonic MIDI ringtones and .amf or whatever that stupid audio format is called ONLY. There is also no known software for Macintosh that will speak said stupid audio format. And since the SL55 doesn't have Bluetooth, there's no way to get data on there from a Mac (cable requires proprietary Windows software I'm not sure works under Virtual PC) except *maybe* IrDA.
The keyboard on the SL55 sucks, too, it being a slidephone with the recessed keys. If given the choice, get the S55: Bluetooth and a good keyboard, but over two years old.
If really given the choice, go for the S65: absolutely brilliant phone (though it, too, won't speak mp3 nor aac for the time being, but it does .wav). (You can find my raves on the S65 in this forum and the lounge. I'm *really* loving mine.)
Avoid slidephones. Their keyboards usually aren't useful, and they have a habit of multiplying when you drop them.
-s*