Well, I may be able to do one better- confirming that there is no 21:9 support in 2.80.
Namely, look at the attached image. Every PS3 version has the layout of the XMB (with resolutions, alignment, etc), in the firmware. Needless to say, the largest is 1920x1080 (its inside the 1080 file), no reference to anything larger (and yes, I am running out of HDD space!)
I highly doubt that they scaled it up - its much more likely that they did some other upgrades, namely the PS2 emulator - from 2.76 to 2.80 it HAS been upgraded.
The main changes from 2.76 -> 2.80 are the XMB (vsh), and the emu's. An excerpt is posted below:
Now, the #'s next to the name are the revision numbers, as you can tell, the largest increases are in the XMB (vsh) as well as increases with the EMU's.
I suppose 3.0 may let us know of any suprise(s)!