To quote: Guys, take a look at my ps3dm-utils. Now you can enable service mode from Linux. Look at ps3dm_usb_dongle_auth.
What service mode can do for us? Well, there's many but i think the most useful one is the downgrading function where you can downgrade the PS3 firmware to the older versions. From the look of it though, it still requires USB dongle to get the job done, correct me if I'm wrong since i didn't look further enough to verify this. Anyhow, can't wait for the release of the noob proof PS3 Linux, OtherOS++.
Update: Jess has confirmed that USB dongle is not necessary to get into the service mode. No you donĀ't need a dongle! You can invoke it from linux. All the modules comunicate throught dm proxy.
Now you can simulate a dongle through software and authenticate through linux. You can generate the challange and create the adequate response.