I use run keeper on my android htc desire z (with3) which uses gps to record distance and speed when running or walking. Does gps use my data allowance. Reason I ask is I am going to Bulgaria and Greece this year on holiday and would use run keeper but not if it's going to cost me a fortune.

Using GPS itself won't use any data.

You may find that the app itself will try to but as long a you've turned off the connection it won't be able to.