+1  A: 

No. The App store accepts apps submitted with production tools only. The latest production tool is Xcode 3.1.3 with iPhone OS SDK 3.0.

You shouldn't expect to submit apps built with Snow Leopard until that product is officially released.

cdespinosa
A: 

nope.

that's why I'm testing betas and developer seeds on my older 20" iMac.

consider it as good practice to develop and test your apps on the current plattform. might save you some trouble.

Jaroslaw Szpilewski
A: 

Logically, you are making an application bundle to send to the app store - if the 3.0 release bundle built by XCode in Snow Leopard is not the same as one built by the Leopard version, then that would be a bug.

Apple does not know nor care what you built with (after all, you could be hand compiling files if you like) so long as the final build meets the signing and execution requirements of the app store.

Kendall Helmstetter Gelner
A: 

Yes. The latest versions of two of my applications (now on the App Store) were built on Snow Leopard, Xcode 3.2, and the Snow Leopard version of the iPhone 3.0 SDK. I tested thoroughly on existing devices, and the behavior (including codesigning) appeared to be identical to what was produced on my Leopard build machine. Of course, the 3.1 SDK cannot be used for submitting applications for the App Store right now, but that's besides the point.

That said, this is probably not a recommended strategy, so I'd suggest waiting a (short) time until the official release of Snow Leopard hits the streets before attempting this.

Brad Larson