PipeRush is a fun little title that we haven't yet seen the likes of (as far as I know) on the iPhone. I remember this kind of game as Pipe Dream, though you may know it by a number of different names. The idea is that you're given a queue of pieces, and then your job is to assemble them in such a way that they all match up and allow water to flow within a certain time period. PipeRush doesn't add too much to this formula (though there are some power-ups to play with as you go through the levels), but what it does bring is a nice bit of polish. There's a cute lead character in Pippa, the pipe-laying plumber, and the graphics are simple and sparkly as you go along. Achievements and scoreboards are handled by Crystal, but with star ratings to chase across the game's 15 or so levels, I found plenty to do.
PipeRush is only US 99 cents on the App Store right now, and if this kind of gameplay appeals to you at all, I highly recommend you pick it up.