Geohot did the the right thing. Face the facts and give both sides some credit.
CDT's greenpois0n exploit doesn't apply for the new bootrom 3GS. Shatter isn't known to Apple yet, therefore they can save it for later. Shatter potentially can work with later hardware revisions, (think original bootrom 3GS versus the new bootrom 3GS). If Apple revises the current iPhone 4's bootrom, Shatter should theoretically still work. Furthermore, Shatter only works with A4 devices (iPhone 4, iPod touch 4G, iPad and the new TV ONLY). iPod touch 3G, iPhone 3GS new bootrom will not work.
On the other hand, Geohot's limera1n exploit will not survive the next bootrom. Apple already knows about it. But it does work on ALL 4.1 devices. iPhone 4, iPod touch 3G and 4G, iPhone 3GS new bootrom and iPad. It should theoretically work on the new TV too but it hasn't been tested. Geohot will also make it work for iPod touch 2G. Think about it, why waste an exploit that Apple doesn't know about, only works for A4 devices and also works for future hardware revisions (Shatter) instead of just using an exploit that works for ALL devices that can install iOS 4.1 and Apple already knows about?
I thought Geohot just wanted to get attention and all that stuff but I was wrong. Read into what MuscleNerd, Comex, p0sixninja and others have been tweeting. Geohot's exploit won't last and works for all devices. It would be a waste to not use it while you can. Shatter should be saved for later, it can work with future hardware and giving it to Apple right now is pure stupidity. Also, Shatter doesn't work for iPhone 3GS new bootrom, iPod touch 3G or 2G.
To sum it all up: Geohot's exploit has a deadline because Apple knows about it. It supports ALL devices (iPhone 4, 3Gs with new bootrom, iPod touch 2G, 3G and 4G and ipad)
Greenpois0n/Shatter is not known by Apple, has the potential to work with future hardware revisions, and only supports A4 devices.