Ok guys, the deal on the 4 GB Workaround SD cards is this:
First off, for the many people saying they don't exist, there ARE 4 GB SD cards that are not HC, this is how the 4 GB Workaround worked in the first place.
Now for the good parts. I followed the instructions on the CAG forum post about the 4 GB workaround. I even used the same one they pictured (the $10 Transcend 4 GB one that says 133x on it, whatever that means).
There was one difference that may be key in what I did and what most people do. When I bought this 4 GB SD card, I had an official Wii 2 GB SD card that was already filled (less than 100 blocks free) - filled to the point that I had to keep some of my WiiWare and Virtual Console titles on the Wii's Memory (which was also full except for 200 blocks) and not on the SD card.
So when I did the work around, I didn't have to pad it. After formatting it with the program the CAG forum suggested, and copying the contents of my 2 GB SD over, it was less than 2.00 GB and I never padded it.
Now either 2 or 3 weeks ago, I had EVERY song available on DLC (I haven't downloaded since then except for today). So this work around worked great. However, the update came (and I was stoked about it) so I downloaded immediately. I was able to delete all my channels off my Wii's memory and have them all on the SD card. While looking around on the internet I saw that there was a problem with RB2 and the SDHC thing so I looked into it. I loaded up RB2. Everything was fine. Went to the store, everything was still fine. I purchased and downloaded Losing My Religion. Everything was fine, it transferred to the SD card with no problems. Went into quick play and played it. Everything was fine. No problems whatsoever.
In the end, I can say this: The old 4 GB workaround cards DO still work. If yours doesn't work, try "padding" it with actual Wii material instead of dummy data. That is the only solution I can offer as mine works fine.