CEO Thorsten Heins has mentioned on RIM's fiscal fourth quarter earnings call today that there are "over one million" PlayBook customers in the market. Considering his verbiage — "customers" — that suggests that over a million PlayBooks have been sold; for what it's worth, "over" 500,000 were shipped in the last quarter alone according to today's earnings release. Heins sounds upbeat regarding the PlayBook 2.0 update that went out last month, saying over 70 percent upgraded within 30 days and pointing out that the upgrade represents a nice preview of what buyers can expect from BlackBerry 10 later this year.