Most likely, you will use multiple views in your workflow. As of Blender version 2.5, the method for splitting view has changed. By default, you see the perspective view (Figure 1). To add another view, look to the upper-right corner of your current view. You will see diagonal hash marks; this is the area that will allow you to "drag in" another view (Figure 2).
Before you try this, you'll need to realize the difference between the hash marks and the little "plus sign inside a circle" icon. If you click or drag on the "plus" icon, the Properties panel will appear. If you accidentally already did that, hit "N" to toggle it off. Either way, try it so you know the difference between the two hover icons. This "plus" icon will give you cross hairs with horizontal arrows as a cursor. The hash marks will give you cross hairs only as a cursor.
So now, to add another view, simply hover your mouse over the hash marks, and you will notice your cursor turns into cross-hairs. LMB-drag either horizontally or vertically to add a new view (Figure 3).
The first thing you will notice (and want to get rid of) is that the Tool Shelf is present in your new view as well. You probably don't need two of those, so hover in the view you want to get rid of it and hit "T" to toggle it off. You can also hover your mouse over the right edge of the Tool Shelf and drag it back all the way to the left until it disappears. For purposes of space, you may as well hide the Tool Shelf in the first view as well. Hover over the left view and hit "T" again to hide the Tool Shelf from that view (Figure 4).
In the new view, go to the upper-right corner hash marks and this time LMB-drag downwards to split that view (Figure 5). Notice that the Tool Shelf didn't appear this time. If the Tool Shelf is visible when you split, it will appear in the new view, otherwise it won't.
Let's do it one more time. hover over the hash marks in the upper-right corner of the bottom-right view and LMB-drag to the left to split that view (Figure 6).
All good… now let's join the two bottom-right views. You're going to use the hash marks to do this as well, but not necessarily the upper-right hash marks, depending on which view you want to remain. Notice there are also hash marks in the lower-left corner of the view "window." That is, including the menu bar at the bottom. These hash marks are more difficult to see (Figure 7).
If you want to join the views and keep the left view, use the upper-right corner. Try this to see the same "darkened arrow" overlay. Either hit RMB or
to cancel or if you already joined them, split the view again so you can see how to keep the right view. Use the lower-left corner hash marks and LMB-drag to the left to do this (Figure 8).
The rule of thumb is that you want to use the hash marks that are in the view you want to keep and directly in between the two views you want to join. If you wanted to join a top and bottom view and keep the bottom view, you would use the bottom view's upper-right hash marks because those hash marks are adjacent and in the view you want to keep.
This also works for more than just views. Notice the hash marks on other windows and panels. The same rules apply; you can split and join these panels with the same method. Here, I've split the Outliner into two panels. This can come in handy to now change one of these Outliners into a different panel (Figure 9).
In some ways, it's faster than all versions prior to 2.5 with no menu pop-up, but it's also more difficult to get your cursor in a specific spot to split or join the view. Also, as of version Alpha 2, you can't MMB-change the direction during mid-split of the view; once you start splitting the view, you're committed to that direction.