This is for anyone who is tearing their hair out trying to figure out why some of their purchased apps are not showing up in the Market after installing the Modded 2.1 ROM on their MotoDroid. After some reading around, i've come up with an answer; unfortunately it seems there is no workaround aside from reverting to the official 2.0.1 ROM.
The problem is this: the Google Nexus is not currently a production device. Since it hasn't been released, it's OS is currently not "whitelisted" by Google. Apparently, copy-protected apps need the specific OS to be on a "whitelist" or the apps won't show up in the market, plain and simple. A search for a copy-protected app will simply show it as not being in the Market at all (meaning you cannot simply repurchase it even if you are that determined to run 2.1)
Apparently this is done to prevent hackers from installing developer ROMs on their devices and extracting the licensing APK files after downloading the app. While I agree that measures like these ARE needed, given the proliferation of sites like rapid.org where downloads of licensed apps can be found; it does present a particularly nasty roadblock to those of us who like to mess with "leaked" OSes.
I only hope that this DRM doesn't affect "cooked" ROMs that are based on officially released OSes (although it shouldn't) - but I could see a potential problem if the DRM does a check to ensure a particular "whitelisted" OS is running on the correct carrier network. For instance, say a nice MotoDroid ROM is cooked based on a hypotherical 2.1 build with Motoblur for a T-Mobile device. I only hope that the DRM scheme doesn't check to make sure this "T-Mobile" based ROM is running on the T-Mobile network.
I don't believe i've heard of this being a problem with 1.5 and 1.6-based ROMs, but this is Android 2.x we're talking about; I only hope the DRM hasn't become stronger.
It's a very specific few. There are a few apps where you download the app for free, and then you need to download a license file seperately to unlock features. Touchdown is one, I believe Documents to Go was the other one (of the apps I own). The problem definitely doesn't pertain to purchased apps as a whole, as most of them are not copy protected. You will know which APK files you are going to have difficulties with, the app manager built into Astro will refuse to back them up, and they will be marked 'private'
I am sure I am more prone than most to spot incompatibilities, i've got about 100 apps and games installed ATM.
Touchdown is the biggie, if I had thought of this back when I purchased it, I would have purchased it via Nitrodesk's website and gotten a serial number, rather than a downloadable license.
I know it's not a problem specific to my device or account, as I read about all of this at alldroid.org for the most part.
Then maybe I have no protected apps but all 75+ of mine work fine on 2.1
Again (just to clarify for others reading the thread) this problem ONLY happens with copy protected apps. It is NOT a problem per se, it actually means that Google's copy protection mechanism is working. It's just that it COULD present a problem later on with cooked ROMs.
The rest of my apps (the ones I installed before I realized Touchdown License Key wouldn't show up and had to revert to 2.0.1) worked absolutely fine on 2.1 - including games such as Speed Forge 3D