One problem related to transmission not engage has been reported for the 2008 Jeep Wrangler. The most recently reported issues are listed below.
Manual transmission will disengage out of first gear when driving. This has happened numerous time, but the dealer cannot duplicate issues because it is an intermittent default. Most current incident was today after the Jeep had been at the dealer for 48 hours. Called Jeep customer complaint and was told unless the dealer can duplicate the problem there is not a valid warranty issue.