How do I identify what PowerPC apps I use? I have a Mac with Snow Leopard 10.6.8 still installed on it and am seriously considering installing Mountain Lion. I’ve read that from Lion onwards PowerPC apps can no longer run.

My questions are: Is this true? How can I identify what PowerPC apps I currently use?

I don’t want to go to the trouble of cloning my drive and then doing the upgrade only to find some software I rely on will not run in Mountain Lion.
Yes, this is true. 

It's also very easy to identify what PowerPC apps you're still using. To do this, follow these steps. On the Mac which still has Snow Leopard installed:


Click on the Apple Menu
Select About This Mac
In the About This Mac window that pops up, click on the More Info... button near the centre bottom.
This opens up the System Profiler window. In the Sidebar on the left you will see a number of headings and subheadings.
Under the Software heading (it's the 3rd one down) you'll see a subheading labelled Applications. Click on this.
In the main part of the window on the right-hand side you will see a list of apps appear. Be patient as this may take a little while to populate.
Once the list appears, you'll see column headings at the top. 
Click on the Kind column heading (it's the 4th one) and this will sort the list by the kind of app.


Now all you need to do is peruse the list to identify any apps labelled PowerPC and/or Classic. These are the apps that will no longer run in Mac OS X Lion or above.