> Is the filename for the verify procedure always named somehting like google*.html?
I don't know, but here's how I got sitemap.xml to be created the right place. I'm really bad at documenting my own changes, so I've uploaded my original sitemap.php along with the sitemap.php that works with MU.
Please note, that some of the changes probably overwrites some security settings, but let me know if you have trouble. I'm not an expert on this, so please don't get mad if I can't help you :D
Basically, I only made changes to two functions:
sm_getHomePath() on line 369
sm_getXmlUrl() on line 402
I think the problem with sm_getHomePath is that it uses the absolute path which is fine if it hadn't been for MU's structure with mod_rewrites and all.
So I hardcoded the correct paths into the function (line 390 to 395).
This problem also resulted in sm_getXmlUrl trying to place the file in a wrong directory. I want my users' sitemaps to be available in their /files-directory. E.g. someblog.blog.com/files/sitemap.xml. So again, I did some hardcoding into the function. Please see lines 415 to 419.
Hope it helps - it works fine for me anyway :)
Original sitemap.php: http://www.studinski.dk/sitemap.txt
WPMU sitemap.php: http://www.studinski.dk/sitemap-wpmu.txt
I use ITDamager's htaccess.
Also, the blogs.dir-directory have been CHMOD'ed recursive so all new blog-directories are writable by the sitemap-script per default.