Unofficial U.S Playstation Magazine PSM are saying that Liberty City Stories will indeed have snow as a weather effect, this was rumoured months ago after it was noticed in the background of a screenshot, however due to the poor quality it was debatable whether it was snow or not.
"This weather effect is actually new to the GTA universe, not just Liberty City. The one thing to keep in mind is that it will actually affect the driving physics, as the roads become more slippery."
PSM also claim to have actually played the played the game which could mean that many other magazines are also getting similar previews. Finally, they say that the only loading times are starting up (obviously) and travelling between islands.
PSM Issue 102 goes on sale early Sepetember
Thanks to GTAPSP for the heads up.