IMG and DIVs Stripped with External Posting Since WP 2 Upgr (Delicious/MarsEdit)

Since I have upgraded to WordPress 2.0 (and to the K2 Beta Two theme), I have found an alarming “symptom.” It appears that incoming posts from an external source — either an external weblog editor such as MarsEdit (a popular Mac OS X blogging client) or from Del.Icio.Us’ automatic daily blog post — have information stripped from their tags.

For example, from MarsEdit, I posted a weblog post that had an image. When I looked at it, instead of being posted as:

[IMG SRC=”http://www.blah.com/blah.jpg”%5D

It had instead posted as:

[IMG /]

And, in a somewhat similar mechanism, when del.icio.us automatically posts its information, instead of posting as it usually does:

[ul class=”delicious”]
[div class=”delicious-link”]
[div class=”delicious-extended”]
[div class=”delicious-tags”]

these instead appear as:

[ul]
[div]
[div]
[div]

Please note that in the latter case, there were the appropriate closing tags.

I would imagine that this probably has something to do with WordPress’ XML interface, or with an obscure setting I need to switch.

Can anyone suggest to me what needs fixing here?