there's evidence that they did work on more versions of OS2008 (one single file of build 2008.47 even got published as a hot fix), but for some reasons decided not to publish them and stop OS2008-related work eventually.

to be honest, though... from my POV there's only a few bugs in modest that would need fixing, but i use claws to work around them. although i would love more OS-upgrades and don't fully understand nokia not providing them, i have to admit the reason i want them is more the kick of "gimme something new to play with", not so much the real need for improvements.

my upgrade path will be OS2008=>Mer, probably. i have more trust in the developers of Mer: They don't need to have a working business case behind their work but can do what's good and what's right.