The use of cell phones is having an increasing effect on survey estimation, particularly for populations like renters and unrelated adults sharing a home. See this report:
Wireless Substitution: Preliminary Data from the 2005 National Health Interview Survey
However, another study by the Pew Research Center for the People and the Press reminds us that cell phone only households are only a small percentage of the population, so excluding cell phones will not have much effect on survey results. On the other hand, there are some situations where the difference is probably greater -- a recent IPOR survey (report in progress) indicates most construction workers in Orleans Parish, LA are probably using cell phones brought in from outside the area.
IPOR can include cell phones in samples that cover wide (generally multi-state) areas but they are problematic for more localized surveys since people move cell phones from one area to another. And even in wide area surveys there are many problems (for example, some respondents will have to pay to respond to the survey, or even to say they do not want to do it).
IPOR primarily uses these packages, but can produce and convert data sets to and from almost any format.
National Network of State Polls (NNSP)
American Association for Public Opinion Research