These are good news mainly for so called agglutinative languages like Turkish, Japanese, Georgian and many others like of course Basque, where most words are formed by joining morphemes together.
As you proposed now it is possible to create a place in Google Code or SourceForge where everybody can put and download spelling dictionaries for Upp (mainly with BSD like licenses ).
Just to remember that uppsrc/MakeSpellScd package lets to compile a UTF-8 (without BOM) text file with a word per line into a .scd file.
One good thing would be to document this or/and add a small sample about how to use the spelling technology into a program.