From what I've learned over the last few days, each plugin is placed on a single line (or row). That's how the Homescreen layout is designed by Microsoft. That way, you scroll up and down to access each different plugin.
Now, my Moto-Q Verizon phone came with what appears to be a special plugin that allows you to define two "shortcut" icons on the same row where you can define an application name and arguement list for each plugin. I customized these two shortcuts to bring up Internet Explorer with two different web pages. Since this is a single plugin, the two shortcut items could be placed next to each other on the same line.
So, I don't think you can put two distinctly different plugins on the same line on the Homescreen. You would need a special plugin that was able to communicate to other multiple plugins to get that to work, and that would be quite a tasks from what I've discovered!
Having said that, it shouldn't be too difficult to write a plugin that had the profile and bluetooth items on a single line (similar to the special VZW plugin that I mentioned previously). I'll see what I can do about putting it together as my "first" plugin project.
The most difficult part of plugin programming, appears to be parsing out the XML code that handles the formatting, positioning, etc. that the plugin must process. Luckily, there's lots of good resources on the net for answers.
ppcinfo