I just got this email from a friend of mine who works in Chikka. You can use your Googletalk client to send to Globe/Smart/Sun mobile phones. To send to a mobile phone, simply add a new contact on your Googletalk client, using the format email@example.com. I just tried it and it does work.
According to the email, the rules of Chikka still apply (P2.50 for replying from your phone). Sending from Googletalk remains free but from what I experienced, if you don’t respond through your mobile phone after 3 messages, your number is blocked from Googletalk.