re: entry #4 - I like the dynamics of the stars. I'm a little worried about the legibility of the font. Unfortunately, the font that you used, the "T" is not very distinct. I noticed that another designer in this contest used another variation of the font, or tweaked with it, so that the "T" is not curved.
Re: entry #20 I like the ticket silhouette. However, I'm not crazy about the background of the graphics for the app being there.
re: entry#15 - we just can't use any logo with the mouse silhouette. Copyright issues.
i just think this one has good potential. Simple enough and colorful (draws attention). I think the other designers should consider that when this becomes an iPhone app icon the corner will be rounded and the "shiny" effect will be added.