When changing employers, HIPAA regulations can often eliminate any preexisting condition exclusion, so you don't necessarily need to elect COBRA if you are "HIPAA protected". When joining a new group plan, you get credit for previous health insurance coverage and can use it to reduce the exclusion period. This is one of the reasons why electing COBRA if you are NOT leaving for other employment is so important...it will continue your creditable coverage so that when you DO get another job, you won't have to wait out the preexisting condition period.

http://www.cms.hhs.gov/hipaa/hipaa1/content/hipsteps.asp#Step3