I believe that zcache could benefit the Galaxy phones by 1) allowing more ram for apps and 2) by allowing more FS objects to stay in cache by means of LZO compression. ext4 supports zcache/cleancache. I.e if "cached" is 15MB, then actual memory usage would probably be 4-8 MB. By reverse, you could fit 30-40MB in 15MB cache.
Zcache should be beneficial for both low-end and high-end systems. http://code.google.com/p/compcache/wiki/zcacheIOzone
You need to enable these two in the kernel. They do not work as modules.
The second option I'd like to see is zram. This can be used as any normal block device, or even as swap. It uses LZO compression, which is very fast. For example, using as Swap, you would typically see 25-35% compression rate. 150MB swap would use maybe 40MB ram.
You can use zram as module (gives possibility to choose size etc with modprobe).