Nope, it never was a blackpowder cartridge, the naming practice is the only relationship to blackpowder cartridges.
Tim
The name .30-30 followed the prevailing practice of that period where the first number designated the caliber in inches and the second number the powder charge in grains,
however, in this case, the second number denoted the charge in grains of smokeless powder used rather than black powder as with such cartridges as the .32-40, .38-55, .45-70, .45-90, etc.[/color]
http://www.leverguns.com/articles/3030history.htm
Although the original name is .30 WCF, the -30 in the designation was added to the name by Marlin, who did not want to put the name of rival Winchester on their rifles when they were chambered for the cartridge soon after its introduction.
The -30 stands for the standard load of 30 grains of early smokeless powder, which was on par with IMR/DuPont's 3031. Over time Marlin's variation on the name stuck, though ".30 WCF" is also proper.[/color]
http://en.wikipedia.org/wiki/.30-30_Winchester