I did this earlier today, on my ATT 8310, gained 3MB from removing PTT and media, they are the only 2 I have done so far. I have noticed a little pickup in speed.
One issue I noticed is that it cleared my icon on my folders I made on the BB apptop... I had a folder for my games, mail accounts, and Junk (stuff I dont use very often but didnt want to trash or hide. So anyway each one had a different Icon, and now they show up as brown boxes lol AND I LOST ALL ICONS so I cant change it to something different lol