Reproduced on 3.2.1 and 3.3
When I setup my WP main host, I can post something like this to the blog:
http://vncaudio.com/2011/12/09/test-single-site/ (3.2.1, nginx)
http://ksstorm.com/2011/12/09/wp-3-3-single-site/ (3.3RC2, apache -- same behavior under 3.2.1, apache)
However, after I enable multi-site, the posts look like this:
The <OBJECT> tag and its contents have been dropped....missing from the database, as well. Adding the multisite xmlrpc plugin does not change it -- the OBJECT tag is still dropped.
In each case this is a fresh install with no plugins enabled, twentyeleven theme. Running on Debian Squeeze.
3.3RC1 is on PHP 5.3.2-1ubuntu4.10 with Suhosin-Patch, mysql Ver 14.14 Distrib 5.1.41, for debian-linux-gnu (x86_64) using readline 6.1, apache 2.2.14-5ubuntu8.7
3.2.1 is on PHP 5.3.8-1~dotdeb.2 with Suhosin-Patch, mysql Ver 14.14 Distrib 5.5.18, for debian-linux-gnu (x86_64) using EditLine wrapper, 1.0.10-1~dotdeb.1
(Cross-posted in the multisite forum area)