One of the changes that seems to have happened recently is the way that hands are moulded, cast and joined on to models such as space marines. Below is a picture (taken from the assembly instructions of the recently newly boxed space marines) illustrating what I mean. Notice how the hand holding the trigger (the right hand -- and don't get me started on why every space marine is right handed!) is not longer a part of the arm, but part of the gun piece itself.
This is at variance to how (e.g.) chaos space marines come off the sprue. With chaos marines, the bolter is a totally separate piece and includes the trigger handle itself (should you want to attach it to the leg for instance whilst the hands hold a pistol and chainsword). The one issue with this, of course, is a reduction in the readiness with which bits can be exchanged between kits like space marines and chaos space marines.
Why am I bothered about this? I'm not too much as its only a little bit of extra modelling work. But since I'd like to blend the bits from space marines and chaos space marines - especially with an eye to constructing pre-heresy styled models - it just mean fractionally more work whereas it was easier earlier.