bugcat: I think that if we're going to add new Korean professionals, we should try to agree on a romanisation policy to at least some extent.
Here are precedents I can see.
1. Whatever is already of long standing on the page in question.
2. "De jure SL style". McCune?-Reischauer, used by Charles Matthews in the early articles ca. 2002.
3. The official current system of South Korea, the Revised Romanisation.
4. Whatever the player is named on their profile on the federation site.
5. Whatever the player is named on the Perfect Weiqi Database.
6. Whatever they're named on Go4Go.
7. What name they're publishing books and / or other content under.
I'd like to use RR with hangul followed by MCR in parentheses and then any divergent romanisations with a link to where they're used, like
"Lee Sedol 이세돌 (Yi Se-tol, Li Sedol) is a ..."
We could also add hanja if that would be worthwhile, but I don't know how much they are in use. If they appear a lot in Chinese / Japanese material then it would be worth it.
By the way, the secondary form Wikipedia gives is Lee Se-dol, which I hadn't even considered.
tapir: See romanisation. (forum page has a discussion about this topic).