It's possible to do 3D plumbing design with ABS 2006. I recently did it on a project... I had one day to do it and I figured it would be less time consuming to figure out how to do it in 3D than to do the floor plan, isometrics, etc.
But you do have to do some manual set up work before hand.
1st open up the mechanical piping system definitions.
Right click on the "Pipe Definition Systems" in the left hand column and click "New"
Set up your piping layers (ie Domestic Cold water, gas, hot water, sanity sewer, etc). DO NOT start with any of the mechanical piping as a basis.
On the next tab "Design Rules" enter in the abbreviation, but do not specify a system group, the only ones available pertain to mechanical piping. The set your layer key and then manually set up the discipline designator (P), then the major and minor 1. You can set all of them up, but it's not necessary.
This is where it gets tricky (and took me about 30 minutes to finally figure it out). At this point, hit apply and then "OK" or just hit OK. Now go to "Add Pipe" and draw a section of pipe for each new pipe you created. Don't worry about the color or linetype at the moment... Don't worry about connecting the pipe to anything, just draw the pipes on the sheet.
Once that is completed then open the "Piping Systems Definitions" again. Click on a pipe you just created, ignore the 'Rise/Drop" and "Other" tabs and go to "Display Properties" tab.
You will see a list of 8 items that start with "1 line" check the box in the "Style override" column and then click the "Edit display properties" icon in the upper right hand corner. Highlight all display properties in the box and then specify your standards for the "Layer" (this is why it's important to draw the pipes you created, once you draw them, then the layer will show up in the list, if you haven't drawn the pipe yet, then the layer will not appear) "color", "linetype", "lineweight", and "LTscale".
ABS is not as intuitive for the plumbing in 3D as it is for the mechanical, but let's face it plumbing design is considered the red headed step child of the industry...
Hopefully the attachment will work... I've attached a portion of a job I did in 3D. Included is the model tab, work tab, enlarged tab and a sanitary sewer isometric. Once I did the design in 3D, then all the rest was just a matter of changing the settings, for example for the iso metric, I changed the setting from ABS Ceiling -2 to ABS ISO -Schematic, then I clicked the "Model" button at the bottom of the page and changed the 3D view to SW isometric.
Now I'm working on getting the schedules to work properly and that is a task in and of itself.