In cydia I click on selections and the repositories folder and it has a check next to Sauriks Source and I go into manage sources and it doesn't show up! It's not there, I tried reinstalling but it still doesn't show! It's happened to a couple of the sources you get when you get cydia, I still have like 5 still though that show up in the sources like bigboss modmyi. I'm on iOS 4.1, 3G iPod touch. Is there anyway these sources without removing them, because it gave me a warning and am trying to avoid having to restore.
Same weird thing happened to me (iphone 4 iOS 4.1) yesterday, and even after several reboots, it still did not come back and also wasn't showing my stored SHSH's.
I decided to leave it till this morning before looking for a solution, as it may mean that @Saurik is making some modifications to cydia.
Well, I woke up this am and opened up cydia and there's nothing there still, so I did a reboot and....voilą! It's all back!!
I guess my first assumption may be correct....maybe a reboot now would work for you too