Foursquare is battling for your SXSW check-ins with a musical scavenger hunt. Rival Gowalla is going to go after them with free gadgets – specifically free Palm Pre Plus and Palm Pixi Plus devices as part of a promotion the location-based social networking service is unveiling in conjunction with their just-launched app for webOS.

The app should hit the Palm App Catalog on Tuesday, and like the company’s applications for other platforms (including its recently launched Android app) it detects your location to show you nearby venues, lets you know where your friends are located, and has a gaming element called “stamps” that can be accrued as you check-in to various places.

The SXSW connection is part of a push by Gowalla into virtual goods. Users will be able to discover virtual Palm Pre and Pixi devices as they use the application (essentially, the more you use it, the better your chances – it’s random), and then be able to redeem those at specific parties at the festival to get the actual device. Another partner – Lomography – has inserted virtual cameras into Gowalla, that once found can also be redeemed for free gear.

This is one way Gowalla hopes to differentiate itself from the competition, and, truth be told, it’s not a bad one. No one wants to leave an event like SXSW empty handed, and by teaming up with brands to offer free gadgets to users at an event that will be loaded with tech enthusiasts could encourage some splitting (or at least doubling up) of the check-ins across services.

Now that Gowalla’s starting to catch up in terms of platform support, much of the battle might come down to marketing – where Foursquare has also recently invested heavily by forming partnerships with a host of media companies.

In any event, here’s a look at some of the features of the webOS app:

Which service will you be using to check-in at SXSW? Let us know in the comments!