Using sketch up models.

[Hacker007]

I would like to use a few models from the sketch up warehouse for a track I am creating, according to Wikipedia the models are open source, I need to confirm this is true and if so what open license is used? Tha ks

[Anon]

The license used is a custom one, specified on their terms of service page.

I'm (very, very) far from an expert in law, but from a quick skim over the license, it looks you can:
Modify the models
Use them as part of something (like a track)
Sell/give away the models, modified models, and tracks "for business purposes" (whatever that means)
Make a "reasonable" number of models, tracks and, modified models (again, whatever that means)

While you can't:
Remove copyright notices
Claim ownership
Distribute the models without modifications (reminds me of CC Sampling, which is not compatible with STK)
Compete with the 3D warehouse
Collect models for redistribution
Use the models in a mapping application

To me it seems that this would make any tracks with 3D warehouse models incompatible with Supertuxkart, but maybe while leaving it free enough for the addons. If I were you though, I'd wait for a developer to give you the go-ahead before using too many of these models.