There is a workaround which my colleague and me came up with. But this workaround is if you want to totaly disable ECB menu for a particular list. Actually there are couple of workarounds, but its upto you which one you wanna go with (depending upon the time constraint).
First is create your own custom web part which will list all the items using SPGridView and then you can customize it as per your requirement and place that web part within a PlaceHolderMain of your custom copy of AllItems.aspx page. For this you will have to remove the View from a List Definition. This is a time consuming process and I would recommend this only if you have to do lot of customization to your ListView Webpart on AllItems page.
Second option is to use a different column to disaply Title column of a list. For any list there are three types of Title columns. a) Title b) LinkTitleNoMenu c) LinkTitle
Now you can set any of these columns in a view of either a List Definition or from the user interface. So ,this way you can decide if you want to have a ECB menu for a particular list or not.