I just removed readahead as well as preload from my Kubuntu 6.10 box. Strangely, this reduced my boottime from 1:11 with readahead enabled to 0:51 without it.
So I guess Edgy with Upstart doesn't benefit by readahead. On the other hand, It could be that my box doesn't have enough I/O speed to make readahead worthwile. I run Kubuntu on a AMD Athlon 1.2 GHz processor, with 786 MB of RAM.