I think the OP is referring to the VCast Song ID app.
I use it on my Storm and love it (its a great way to win an argument!).
One of my co-workers has a curve and wanted the app. It does not show in his VZW web page on his device. I sent him the link from mine, and it wouldn't install on the Curve.
My guess is that it isn't written for that model.
Blackberry Storm2 (Verizon)