Yes, it can. In a wedding, I used an Alzo bracket, having ST-E2 on the camera and a 430EX II on the bracket. It worked. However, it's in a room. So, it may be bouncing the infrared signals around. I don't know if it works in open area.
Infrared of ST-E2 actually is quite good when in a room. Today I took pictures of a mini-concert in school inside a room of about 40 people. Three Speedlights were located as far away from each other as possible. One Speedlight was behind me. It still worked.
I can do a test outdoor with the gear if you really need to know. But I live in an apartment, not a house. It's quite cumbersome to bring everything outside and assemble, just for a test.