Thanks to Joar, I saw Matt's posting on this a while back and Chris Espinosa's answer. OK....
But here's what I am seeing on XCode 3 launch.
This is a very vanilla Leopard system - NO foreign software at all...
3/18/08 8:27:39 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x2963030, has non-zero refcount = 1
3/18/08 8:27:39 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x2963d90, has non-zero refcount = 1
3/18/08 8:27:39 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x2963030, has non-zero refcount = 1
3/18/08 8:27:39 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x2963d90, has non-zero refcount = 1
3/18/08 8:33:16 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x31cfed0, has non-zero refcount = 1
3/18/08 8:33:16 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3725640, has non-zero refcount = 1
3/18/08 8:33:16 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x30ed7e0, has non-zero refcount = 1
3/18/08 8:33:16 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x31a9610, has non-zero refcount = 1
3/18/08 8:33:16 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x31cfed0, has non-zero refcount = 1
3/18/08 8:33:16 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3725640, has non-zero refcount = 1
3/18/08 8:33:16 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x30ed7e0, has non-zero refcount = 1
3/18/08 8:33:16 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x31a9610, has non-zero refcount = 1
3/18/08 8:33:18 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x318bda0, has non-zero refcount = 1
3/18/08 8:33:18 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3245320, has non-zero refcount = 1
3/18/08 8:33:26 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3047dc0, has non-zero refcount = 1
3/18/08 8:33:26 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x308a7c0, has non-zero refcount = 1
3/18/08 8:33:18 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x318bda0, has non-zero refcount = 1
3/18/08 8:33:18 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3245320, has non-zero refcount = 1
3/18/08 8:33:26 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3047dc0, has non-zero refcount = 1
3/18/08 8:33:26 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x308a7c0, has non-zero refcount = 1
3/18/08 8:34:05 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x34d2750, has non-zero refcount = 1
3/18/08 8:34:05 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x34ef4d0, has non-zero refcount = 1
3/18/08 8:34:05 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x34d2750, has non-zero refcount = 1
3/18/08 8:34:05 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x34ef4d0, has non-zero refcount = 1
3/18/08 8:34:50 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3292dd0, has non-zero refcount = 1
3/18/08 8:34:50 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3295380, has non-zero refcount = 1
3/18/08 8:34:50 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3292dd0, has non-zero refcount = 1
3/18/08 8:34:50 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3295380, has non-zero refcount = 1
3/18/08 8:35:12 AM momc[685] momc compiling for 10.4 target
3/18/08 8:35:22 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x35848b0, has non-zero refcount = 1
3/18/08 8:35:22 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x358bc40, has non-zero refcount = 1
3/18/08 8:35:22 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x35848b0, has non-zero refcount = 1
3/18/08 8:35:22 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x358bc40, has non-zero refcount = 1
3/18/08 8:35:50 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3432ea0, has non-zero refcount = 1
3/18/08 8:35:50 AM Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x345e130, has non-zero refcount = 1
3/18/08 8:35:50 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x3432ea0, has non-zero refcount = 1
3/18/08 8:35:50 AM [0x0-0xd00d].com.apple.Xcode[110] Xcode(110,0xb0103000) malloc: free_garbage: garbage ptr = 0x345e130, has non-zero refcount = 1