I'm sure someone did, BTW this was discussed here a little while ago, search on dynamic RAM. If you want to use dynamic RAM, you will have to include refresh code in your '51 which, of course, can be done; however it must be prioritized so that all other interrupts will increase their latency.
Do not accept this as gospel, this is a recollection of how to refresh the RAM: every 5mS you must read from every column of RAM (typically scan through all address bits - 00...01B to 10..00B). If you have an application requiring that much RAM and dynamic RAM is what you will use, have a look at the Philips "16-bit '51" XA-H4, it has the RAM refresh circuitry in hardware and 16Mb addressing capability.

Have fun,

Erik