Ah, finally!
I have been struggling with the SainSmart on Arduino IDE version 1.0 also. I've tried several "new" LCD libraries which include I2C connections. Much of the results led to a dark, blank display with a flickering backlight. Some just remained blank. I've been through the wire library changes send/write, various init() or begin() options, and tried compiling a lot of the examples with several versions of the I2C libraries. I can compile and run the "sainlcdtest program. To do this I must first delete the LCD library that is supplied with Arduino 1.01 and then expand the rar file to replace the entire LCD library. However, when I change the program slightly, to display line 0 as a String rather than a quoted constant, the display goes back to blank with a flicker of the backlight.
Be sure to delete the original LCD library and completely replace it. If Arduino 1.01 finds the original library it will cough up a whole bunch of errors about already defined or redefined functions.
As I recall, the first error usually is that:
LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
is not valid. Means that it is using the wrong LCD library. All in all I'm not happy with the attempts to replace the LCD library with one that includes I2C.
I'm still using Arduino IDE 0022 to develop my program and have an Adafruit 20x4 plus I2C backpack to test some of this stuff as well. I'll post more after getting the results organized. I've been working on this for two weeks and managed to completely confuse myself.