[tlug] MySQL 4.1.15, or MySQL 5.0?

[Dave M G <martin@example.com>]

TLUG,

I originally asked this question on the MySQL mailing list, but it got 
no response. Perhaps it was considered beneath them, as it's a pretty 
low level question. Perhaps the ever-helpful TLUG can set me straight:
Currently I'm running MySQL 4.1.15 on my home computer where I do web 
development, and MySQL 4.1.13-beta on my hosting service. Actually, I do 
work on web sites that are hosted on many hosting services, but on only 
one of them do I have enough access to decide for myself if I want to 
upgrade the server.
It seems that MediaWiki, something I'm currently experimenting with, 
requires MySQL 4.1.14 or above. So at the very least I need to upgrade 
MySQL on the hosting service.
But I'm a little confused by the presence of MySQL 5.0. On the mysql.com 
web site, it promotes version 5.0 and barely makes any mention of 
previous versions. (Of course, in the support documentation there is a 
lot about previous versions, but I'm just talking about the site's 
promotional text.)
Ordinarily, a new version of any software wouldn't be confusing. I would 
assume that whatever the latest version that the developers are making 
available is the one that is supported and stable and preferable to use.
But none of my hosting services anything higher than 4.1.15. And my home 
computer, which runs Ubuntu, defaulted to installing 4.1.15 and the 
application update manager doesn't update it to 5.0.
So if 5.0 is the "current" version of MySQL, why does it seem to me that 
it's not widely adopted?
Would it be problematic now or later if I upgraded to 5.0?

Would I have to soon upgrade to 5.0 if I upgraded to 4.15 now?

Thank you for any advice.

--
Dave M G