It looks like Hideaki Sorachi's long running manga series, Gintama, is coming to an end, at least for the Western hemisphere, with volume 23. Anime News Network confirmed with Viz Media that it no longer plans to publish the series, and retailers including Amazon, Barnes & Noble, and Borders have it listed as the "final volume."
All hope may not be lost though. The manga's Japanese publisher, Shueisha, is continuing the series in Japan, where the 39th volume was recently released, so there is a chance that another North American publisher may jump in and pick up the series.
Gintama launched in the U.S. in 2007 and has had a fairly successful run and developed a solid following. The anime adaptation can been seen on Crunchyroll.com and Section 23 will continue to release volumes on Blu Ray and DVD.