No, it isn't a themed Gingerbread or Froyo ROM, it's true Android 4.0 goodness on this 3 year old phone. XDA Developer Member tilal6991 has compiled a version of CM9 for this device. No, it's not blisteringly — but nor was stock 2.2 anyway. The ROM is called ColdFusionX and it's available on the XDA forums for downloads. However, the official download links for this ROM has been taken down — but a mirror link of it has floated further down the thread.
It is important to note that there is no hardware accelerated graphics, nor any video recording. But they are no biggies, I'm not going to watch videos or record on my U8150 anytime soon… nor have any fancy live wallpapers.
I did overclock the phone from 600MHz to 652Mhz — with slight improvements to performance. So, that's a step you could take if the phone gets too laggy.
Enough of talking, let's admire the beauty of ICS on this old old phone.