Most chargers have different output values, for example a phone charger will probably not charge a tablet as the tablet has a far larger battery, but a tablet charger can charge a phone, RIM have said the charger for the Playbook will work with BB phones and charges the phones quicker. There should be systems inbuilt to the phone which will prevent overcharging (I emphasize should). Normally you are talking either 1 amp or 2 amps on the chargers.
So in theory you should be okay. All batteries will warm up when charging but as Jay said if it gets hot to hold unplug it and buy the phone specific charger.
Love is better than anger. Hope is better than fear. Optimism is better than despair. So let us be loving, hopeful, and optimistic. And we will change the world. - Jack Layton (1950-2011)
Blackberry PlayBook 64GB Nokia 1020, Microsoft Surface PRO 2