if you want to make sure you can go to system settings. Then I think its system information. and it will tell you the version you have.

I tried this morning to do this but it failed, said I already had the latest version. I'm in the UK so maybe that makes a difference to you North American's that are able to get it. Checked numerous times and I still have 2.36

I can't vouch for anyone who didn't update the firmware before it was temporarily pulled from servers, but after trying unsuccessfully to DL 2.4 via WiFi several times, each timing out, I plugged into my hub via Ethernet and the file took maybe 10-15 minutes tops to transfer.

No need to check system settings; if you press the PS button during video play back or while a PS3 game is running and the XMB appears, it's 2.4.