You'd think that since several of Bukkit's Devs working at mojang on server code and that with snapshots every week showing what changed that Bukkit builds would come faster and more smoothly.
That doesn't happen either. 
And that's becasue of the four that were hired by Mojang, only one is still involved with Bukkit. Dinnerbone and Grum have nothing to do with Bukkit any longer. Evil Seph does becasue Bukkit was his project to begin with.
It's a common misconception, one that I'm somewhat surprised is still being told as fact, especially considering that they have stated via tweets and other methods that they are not part of Bukkit any longer and do not work on it, Seph excluded.
And even if the same people who are working on Minecraft directly, which would be Grum and Dinnerbone, were still part of Bukkit,
what they have access to as part of Mojang could not be used in Bukkit.Bukkit, as it is open source and Minecraft is not, still has to be decompiled from the obfuscated code of the Minecraft server jar. This has to be fixed first as we all know that the resulting code from a decompile, especially when obfuscated, rarely works right the first time. This is mainly what takes all the time, decompiling and getting that mess fixed up and working. Then there is the major bug finding and fixing.
And this is all in their free time, kind of like what happens here, people working on something in their often minimal spare time.
As for the snapshots, you do realize that a minor change from one snapshot to another means another decompile that can be very different from the previous one, yes?