I have a Samsung Galaxy S II but my Ubuntu 10.04 laptop, although it recognizes the phone when I connect it with a USB. won't allow me to get into the phone. Do I need special drivers?
No you don't need drivers! Firstly, you need to enable using phone as mass storage.
You now can now use your phone like you can use any USB flash drive. Mount and explore your files in any file manager (e.g. Nautilus, Thunar, Dolphin, etc.).
On your android phone, go to Application->Settings
In there, go to Wirelessand Network and select USB Utilities
Click on Connect Storage to PC
A message should pop up: Connect USB cable to use mass storage
Now connect the USB cable to computer
A green android robot should be on display with an option of “Connect USB storage“, click on it
The green robot turns orange now and now you can access the files on the SD card of your phone
You do not need any drivers at all; it's all automatic. How you access the phone, however, completely depends on the version of Android and whether or not you are using a custom rom.
Stock (factory) Samsung
If you have never run system updates on the phone before, do the following:
Samsung Android 4.0.4
If you are running Android 4, the phone will by default switch to MTP or PTP mode. From personal experience I've learned that MTP does not work very well at times, as it can make the device appear empty or report connection problems. To use USB storage mode, do the following:
Custom Android roms generally have their own way of doing things. It is important to note that some custom roms don't have mass storage mode at all; I have had cases where resurrection remix roms only had MTP and PTP mode, but no mass storage mode (which is a major reason that I stopped using it and switched to WanamLite instead).
Hope this helps