After some shallow exploration, I have found a template/example for poster preparation in LATEX. It is only one among many, but I pressed on with that particular one almost blindly. I am currently in the process of preparing one poster for a conference I will attend in Arlington, Virginia within a couple of weeks (there will be no blogging in that period).
Ironically perhaps, the author of this ‘TEX forgery’ is currently working at Microsoft. He has been quite a successful researcher and I even exchanged a few E-mails with him. Nonetheless, the scenario is rather odd. Employment in Microsoft lies in complete disagreement to intentions of such contribution to to our LATEX community. TEX often obviates the need for commercial, proprietary software such as Adobe Illustrator.
Upon closer inspection, I discovered that another poster template produces visually-richer results. Yet, I have no experience with this LATEX kit. If you have experience with other such packages and can also comment on them, please post them below for others to benefit from.
Previously, in my younger days of naive existence, I actually created a poster by handling a 6,000×4,000-pixel image in the GIMP. It was rather convenient, to be honest, but making subsequent changes was a tough task. You can find the amateur outcome on this site as a shrunk-down and down-sampled JPEG, as well as a lossy full-sized version. On my hard-drive I retain a ZIP archive which contains the 70-megabyte original bitmap. What a pixelated beast!