Context menu and touch-screen devices

Now that touch-screen devices are so common, it's a bad idea to design websites that uses a custom context menu?

I'm talking about this kind of menus. How iPhone users and Android mobile users see context menus? Are the users able to interact with custom context menus? Which are other bad practices when pro开发者_开发技巧gramming thinking on this kind of devices?

In android..context menu appears (eg. in browser) when we press and hold a particular link or text. I think we can still have context menus except that the event on which it gets fired up is different.