In my personal opinion this is all for the sake of piracy, unfortunately the linux compatibly was disabled by Sony for no reason,It was believed that Linux will enable a boot loader for PS3 games,so they took it away,something that "upset" hackers(it certainly did),but the matter of the fact is that the USB piracy created by the Jailbreak team did not involve Linux emulation and lead directly to piracy(they say game backups,but we all know that is for piracy).
As for "homebrew applications" goes is not something that I'm looking for,all applications that can be done using PS3 hardware can be easily done by Linux emulations,so PS3 will use Linux based system as the original xbox did,and such applications developed at the time now can be done in the PS3 system(Web browsing,music playback,video playback,etc...).
So I like the bit that they say "Linux running on PS3",that was something that the PS3 did loose and something that needed back,but the rest as I said before is for the sake of piracy so there is not too much to look forward, except of course for massive updates,tons of firmware versions and online game hack(just like Socom series on the PSP,which were damaged badly in the online gameplay).
What I found weird is the fact that several groups are attributing the PS3 Key founding,something weird if you think about it(three groups in less than a month?).
Finally as GT5 is concern about this topic(which BTW should not be here),the game will be pirated,but with all of these updates,I don't think that the pirates can get the full amount of features that GT5 updates are giving to players,and I found quite hard to see "pirate" players in online since it requires updates,so GT5 can be pirated,but it can be played as well as a real copy does.
Devedander
Also the ability to sign your own code gives the ability to create viruses... a simple virus could turn millions of PS3's into a huge botnet.
That is a bit apocalyptic if I'm honest,it will require a massive attack in several severs by a large group of people.