I might be wrong - but I cant find a way to get a feature count by release or product.
Report Column Example:
|Product Name||Release Name||Feature Count|
|My Product||Release 1.0.1||21|
|Release time frame|
This can be achieved today through the pivot table. Go to Report Pivot and select the Example report for "Features by release." You can then click "Select data" and "count" the Cell values.
From there, you'll see additional options for other types of math which is possible as well. Hope this helps!