Apparently now that they don't include Max in every game, LucasArts has decided to start including him with games. According to EBGames.com's Armed & Dangerous page, anyone who pre-orders the PC version will get a CD containing Armed & Dangerous concept art, music clips, and the opening cutscene. If that isn't enough, the pre-order bonus disc also includes the full version of Sam & Max Hit the Road!
This pre-order bonus is of course a followup to the Rebel Strike Gamecube bonus disc, which includes a Gamecube compatible version of the old old vector Star Wars arcade game by Atari. Good stuff, I tell you. The Rebel Strike pre-order bonus disc promo is going on at almost every retail chain and online store (in the US at least), so it's probably safe to assume that the Armed & Dangerous one isn't limited only to EBGames. (Update: The GameStop.com pre-order page has a couple more details about the disk and pre-order deal)
Source: Adventure Gamers