I'm beginning to learn flex, and it seems that now is right around the time when the sdk is moving from v3 to v4. I'm noticing that there's not much support or tutorials for the v4 sdk, or maybe it's just me. Is it too early to use the v4 sdk? have most people not caught up with it yet?
If you are learning, then I think it is good to stick with version 3 since, as you say, there are more tutorials and support for it. I don't see any problems in transitioning to version 4 when it is released or you feel comfortable with using software that is still being developed.
If you're not releasing a 'for real' product soon, I personally would go with Flex 4. Obviously, it's still in beta and things change frequently in the nightly builds (which is kind of fun ;-); in fact, a major namespace changed not too many builds ago. However, if you're just starting and have some time, the Spark framework components seem to me to be much 'lighter' and certainly separate the logic from the skin styling in a very nice understandable way. If you want to play a bit, Google "Flex 4 Beta in a Week" and work through the exercises.
On the other hand, if you've not done much OOP or Flash programming before, I'll vote for Flex 3 too as there's a ton of resources out there.
If you haven't started working with the Flex Framework yet, its best you start with Flex 4. There has been a major namespace change, but its for the better. You can also integrate other cool Adobe tools like Flash Catalyst only with the new Flash Builder.