My personal favourite from 24C3: Xbox 360 hacking
I've seen quite a number of presentations live at 24C3 as well as recorded ones in the days following the event. While many of them cover important subjects, there is one lecture that is outstanding: "Deconstructing Xbox 360 Security".
The level of technicality of this presentation was just right. Finally something that went deep down into the technical details. Explaining what kind of flaws they found in the disassembled power PC object code.
I definitely want to see more lectures/presentations like this. Don't be afraid to overload the audience with technical details. Just go ahead with it :)
Also, this presentation has shown how far advanced the game console hacking is compared to mobile phone hacking (at least from what I've seen in the ETC (Ada-developers) and and Motorola hacker communities). The problems are similar: Completely undocumented hardware, cryptographic authentication of code by the boot loader (sometimes down to mask ROM), ...
So I hope that the mobile phone hacker community will grow and more people with this skillet, attitude and time will join. Free your phones!