Should work fine mounting it as a USB device (I've even done that with our iPhone and used it as an HDD). Funny enough, I don't think I've done that yet (but I have my phone media copied over to our media server).
Also, you can use a DLNA server (which serves up media) and I would _assume_ you could consume it from the PS3 since it's "DLNA aware".
Like someone else mentioned, you can always stick the MicroUSB into an SD slot (with an adapter).