Ticket to Ride Pocket, the iPhone and iPod Touch version of the hit board game, is available now on the App Store for $0.99. The title supports solo play, local pass-and-play and local Wi-Fi/Bluetooth. Developer Days of Wonder has been upfront about what's missing from the iPhone version: online is out (because things like phone calls would break the experience, it says) and the level of detail and extra pieces on the Europe and Swiss map expansions don't lend themselves to the size of mobile screens.
The iPad version of Ticket to Ride has been available for a little while for $6.99. There's also the XBLA version for 800 MSP ($10), and the Europe and USA maps available as DLC.
Days of Wonder's adaptations have been incredibly faithful to the game, with the added value of not worrying about all those pesky pieces getting lost.