Apparently, Android4.0/ICS is going to be huge! Now, that's not in the usual "marketing hype" way... obviously it's a really big deal and will probably mark the beginning of a banner year for Android n 2012. You see, it's very large in another way actually... the new Android OS is going to literally be an enormous download. In fact, here are some comments from developers describing it's enormity,
Cyanogen himself indicated while downloading it, “B E H O L D Ice Cream Sandwich, M A R V E L at its colossal source, W I T N E S S it saturate your internet connection.”
Also, another developer, HTCClay, had this to say,
“Be advised, if you plan to work on multiple branches (ICS release, ICS development branch and AOSP master branch), you’ll need to plan for disk space accordingly. You could easily end up using over 250 GB."
Developers need to keep this in mind as it's immense size will take up more hard drive space, as it's a 6GB of download, and 25GB on disk. Furthermore, it is recommended that you use 16GB of RAM or more, and it’ll take 5+ hours of CPU time just to make one build! Wow!

For these reasons, it will take a bit more time for all the community developers to get stuff cranked out for it, so in the mean time, the rest of us normal folk get to be patient. We send great intentions out to our developers. Hang in there guys... we don't want to hear about any "brain-splode"!

Source: AndroidSpin