Anywhere you can find out about upcoming models?

From such dealers as Tamiya and Hasegawa? I know about the R-M site...

Or are the new releases just dropped on the market with no warning?

the only one i know of is the revell company and maybe the tamiyausa site that i know of i am new so i am not totally sure

Most manufacturers have their own websites where they announce the upcoming releases.

www.tamiya.com
www.hasegawa-model.co.jp
www.italeri.com

To name but a few.....

It never hurts to use the search powers of google.com either.

Ray

Hobby Search (http://www.1999.co.jp/eng/plamo/) and HLJ (http://www.hlj.com/) are also good sources. HLJ has a list of future car and bike releases and HS will list the upcoming items under the relevant manufacturer for you to reserve, take a look at the Fujimi car list for example.