Yeah, I also have this bug with Forge 605, default texture pack, with and without Optifine. Blocks in frames show up fine, but the 3D items do not display.
Confirmed here as well. Forge build 583 with no other mods and TNT minecarts roll right over the activator rail as if it was a normal rail. Works fine with vanilla 1.5.
The Minecraft Realms feature that was added in 1.5 adds a new button to the main menu of the game. It seems that Forge's Mods button tries to occupy the same space as this new button, so you are only able to click the button that decides to show up at the time.