Can a GPRS Phone cause harm to a WAN

I would be interested in your feedback and experience with all the emerging technologies in Mobile telephone which can now run JAVA apps, access the WEB via GPRS and then perform a Sychronisation with your mail server to upload and download calendarappointment etc. Is the WAN exposed to virus threat and other impacts, or is the statement one influenced by paranoia…all your feedback is welcomed and references to whitepapers and other would be greatly appreciated