Where are intrinsically bursting neurons found in the mammalian brain?
One very notable example of intrinsically bursting neurons are the thalamocortical relay cells.  They have a hyperpolarization-activated calcium channel which leads to periodic bursting at delta frequency.  The hyperpolarization activation allows these neurons to switch from tonic firing (esp. during wakefulness) to burst firing (esp. during sleep).  The bursting of these neurons has been associated with schizophrenia (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2802545/) and have even been fingered as the root of consciousness (see the work of Rodolfo Llinas).