I have a document that looks something like this:

Some Type of Title: Here is some text that automatically wraps when
it is needed, and it is not bold, like the title is. Basically this would be
accomplished using a text area with the first few words bolded, but I don't
think that SVG supports bolding text mid-sentence... at least not without
creating a new text object.

I just want to make it easy for a user to edit a template so she doesn't need to type into multiple lines. Any tips?
(I will also be trying to alter the document programmatically, so she just fills out a web form and PHP edits the .svg file, so if there are any cool API's or things I can use with PHP to accomplish a similar feat, that'd be awesome too.)

Inkscape can indeed bold substrings and by putting the text into a shape the text will wrap automatically - http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Text.html

PHP5 has native support for editing XML files (such as SVG). You can read some tutorials about this here - http://www.devshed.com/c/b/PHP/ (refer to the ones about DOM XML Extension).