Warcraft III is Universal, so it will work if it's already installed and you're installing Lion on top of SL. If you had WC3 installed and are doing a clean install of Lion, you can burn or copy the WC3 game folder (or if you have it on a Time Machine backup, all the better), then copy the game folder back over once Lion is installed.
The Installer.app for WC3 on the other hand is PPC, the one you download from Battle.net is also PPC, so you can forget installing WC3 after installing Lion.
Diablo II and Starcraft 1 you can forget about in Lion.
World of Warcraft and Starcraft 2 are fine (Diablo III will be as well).
There's a possibility that Blzzard "might" make an updated installer.app for WC3 for Intel, but that's a MIGHT.
Also, as one of the above posters highlighted.....it's not just Blizzard games, but all PPC games.