Solution 1:

John Gruber recently posted a link with some more information from his research over at Daring Fireball: pastrykit

EDIT: David Calhoun added a lot more in-depth information over at this blog: pastrykit digging into an apple pie

Solution 2:

To find more info, a UML, Full Decoded/Decompressed Source and Assets check out this entry: apples pastry kit iphone javascript toolkit

Solution 3:

It would appear that PastyKit is also in use in iTunes LP files. Fascinating. Can't wait to learn more about this — sorry not to have more details!

Solution 4:

In pursuance of PastryKit, I've discovered Sencha Touch. It's buttery smooth on the iPad. At this point in time, it is definitely more fluid than Apple's AdLib js lib (as used on the iPad User Guide site). Try their demoes on an actual iPad to have a real feel for the framework. It must be relatively new, because I find no mention of it among the other mobile JS libs.

Testing for "smoothness" on my iPad, it beats:

  • jQTouch
  • PastryKit/TuneKit/AdLib
  • WebApp.Net (mentioned in another post)

IMO, WebApp.Net is the next most native-like when it come to scrolling, clicking, sliding, etc. These are the most serious competitors I've tested.

Random sidenote: I'm a tad surprised Apple would name a mobile JS library PastryKit with Android's naming convention of desserts.

Update 10/3/2010: The relationship between Sencha Touch and jQTouch explained by their developer, Sencha.