The projectmanager left and I wanted to produce a poster and did not have a lot of time. It had to at least contain the screens of our webapp and some photographs of the team, I also wanted to include most of the graphics we produced for the presentations of the product in the past year. Now I knew that doing this in Photoshop like you are supposed to would have cost me a certain amount of time, that I, also due to the deadline which was connected to the managers departure, did not have. So I tried it in Keynote, a presentation package. I figured that if I could make a slide of a high enough resolution, and then export this to PDF, the printer could plot a sharp enough poster out of it.
The big advantage here was that I could just drag and drop the material, line it up using the automated guides, crop the photographs and send relevant pieces to foreground and background, and be ready in a nick of time, compared to all the layering work that PhotoShop requires for this (combined with my relative inability to use that program well).
So I defined a 4000*4000 slide with a white background, dropped in the screenshots in the pure uncompressed tiff they were made of, dropped and cropped the photographs and dragged and dropped the pdf vector graphics from the other presentations. The titles I did with very large Zapfino and Hoefler text (200 to 300 picas), and put in some backgrounds unsing the standard geometrical figures.
The machine became a bit unresponsive when I finished up the work, and my impression is that when I started adding graphics with alpha channel there was more work to do for the machine. I exported the PDF to a standard X3 format and went to the printer, who luckily is situated just around the corner. After some initial anxiety when the Sony Vaio machine she ran PhotoShop on took several minutes to load the rather large pdf file, we printed a poster of 1 meter by 1 meter and it came out lovely and sharp, and the lady even remarked that she did not yet see a font that came out this sharp on the Epson plotter that was used. So hey presto, I know how to do it next time.