You can use xargs and the result of the adb shell ls command which accepts wildcards. This allows you to copy multiple files. Annoyingly the output of the adb shell ls command includes line-feed control characters that you can remove using tr -d '\r'.
Examples:
# Using a relative path
adb shell 'ls sdcard/gps*.trace' | tr -d '\r' | xargs -n1 adb pull
# Using an absolute path
adb shell 'ls /sdcard/*.txt' | tr -d '\r' | sed -e 's/^\///' | xargs -n1 adb pull