Let me clear some things up
1.) What's up with writing NDEF tags in ICS?
The issue with writing tags is ICS related. From 4.0 to 4.0.2 you cannot format a blank tag to NDEF. This is fixed in 4.0.3 (confirmed). Once a tag is formatted for NDEF messages you can write WHATEVER you want on it (as NDEF) as long as the tag is not write locked. Therefore, any tags that you purchase preformated NDEF (with a URL, text, anything) will work with any of the market apps that write NFC tags (as they all leverage the same write library and use NDEF).
Tags from Tagstand or anywhere else that are pre-formatted and not write locked will work fine (most shops do NOT write lock, touchatag does, don't buy those).
2.) Does everyone need to buy the app?
No, there is a free version of NFC Task Launcher for executing only. This was added so that *everyone* didn't need to buy the app to use the programmed tags.
I could add an automatic link to the NDEF Messages so that everyone would see a Smart Poster link if they don't have the app installed, but that's an extra 30 or so bytes that would be added to every tag. For people with Ultralight or Ultralight C tags this represents almost all or a significant portion of available space for programming the tag. As a result I did not do this as I wanted to leave as much space as possible for programming actions (some things like launching an app require quite a few bytes).
Other
I do all development on a Nexus S and a Galaxy Nexus - so no worries about incompatibilities there. I just pushed an update to fix some UI issues (things got too small due to the increased PPI and not using scaling width/heights) on the GN.
If you have any other questions I'll subscribe to this thread, just let me know.