Chris, a few more feature requests, since you are generating this on the server side:
a) Consider an option not to pass a gallery, but just () - in this case PBase randomly selects a list of 30 from any of our galleries
b) Consider an option to pass a series of galleries like SLIDESHOW(foo,moo,hoo,noo) - in this case, PBase randomly selects a list of 30 from any of these galleries
Both of the above will be very very useful to keep our viewers always seeing something new
c) Don't stop at 30 - keep overwriting the array with new blocks at 30 (i.e. making the list infinite, but keeping your buffer at 30). I understand this is more of a server load and more coding, so it's up to you.
regds
arjun