There are at least two options for technical support.
The Gumstix community is available for no-charge technical support via this mailing list. Gumstix engineers monitor the mailing list and respond to those questions as suitable, thereby reaching the community at large.
Several companies are skilled in Gumstix technology and may be available on a contract basis for one-on-one technical support and consulting. Gumstix posts a list of some of those companies at www.gumstix.com here