As of right now, it looks like Finale 2009 and 2010 works OK on OS 10.6.

MakeMusic has posted this information to their Knowledge Base:

[url=http://makemusic.custhelp.com/app/answers/detail/a_id/1720]http://makemusic.custhelp.com/app/answers/detail/a_id/1720[/url]

[url=http://makemusic.custhelp.com/app/answers/detail/a_id/1721]http://makemusic.custhelp.com/app/answers/detail/a_id/1721[/url]

[url=http://makemusic.custhelp.com/app/answers/detail/a_id/1722]http://makemusic.custhelp.com/app/answers/detail/a_id/1722[/url]

As Jesse said in the Sibelius topic,[b]use caution when upgrading your OS...[/b]

Also has been confirmed by MakeMusic Support on the forums:

[url=http://forum.makemusic.com/default.aspx?f=6&m=268944]http://forum.makemusic.com/default.aspx?f=6&m=268944[/url]