Here is Maemo member juiceme introducing ubiboot:

Now the first version of ubiboot N9 environment is ready for release. The downloads and documentation can be found from http://www.swagman.org/juice/ubiboot/

– Configurable boot environment that can be used to launch different OS’ses / kernels for N9
– Integrated repair/maintanance mode

With ubiboot you need not ever flash a kernel again, you can use similar procedures to maintain your kernels an on regular desktops, just copy kernel&mudules to device and edit boot list.

With ubiboot it is easy to change OS’es on the fly, you can boot your device to Harmattan/Nemo/Nitdroid without any extra equipment, and select what kernel you want to use with the OS.

Thanks (in alphabetical order) go to at least the following people;
Hurrian, Jonni, Sledges, Stskeeps and propably others 



Source Maemo.Org