Photoshop: Ability to create an image larger than 300,000 by 300,000 pixels

I want to go beyond the Photoshop 300,000 pixel limit to create urban landscape paintings like the one I'm working on here at http://www.gigapan.com/gigapans/216921

Does anyone know if Adobe will increase the pixel image limit soon from 300,000 to perhaps a million

Even at 1.1 GB it takes a while to process anything, I often save as and then purge all (the save as is for insurance).  It helps.  I mostly run files of 100 - 300 MB at a time.

You can reduce the number of history states to reduce the size of the files. But that history takes space, and that disk space is necessary once you run out of RAM.

When I edit some files on Photoshop that are 10 gigs in size they create temp files as large as 60 gigs and eat up my hard drive space. Do you know a way I can stop photoshop from creating these files.

Not much can work larger than Photoshop.
And a few layers in a 300k x 300k document would hit a TB.

But at that size, just opening and saving is going to take hours.

Wish to create single TB size image files

Are there any other software and file formats to allow me to go bigger than PSB?

You don't. That is presently the limit in Photoshop.
(at at 250 Gig for a flag RGB 8 bit/channel image, it's also rather time consuming to read or write)