The UI design has been frozen. I need a couple more tweaks and it will be completely designed and coded. Here's a screenie of the UI having a directory as the source, and the split by line splitting strategy selected:

I created a new forum group just for Text File Splitter. I already posted a Visual Studio template to create new file pattern tokens on the File Patten Tokens forum. This will install a generic template in Visual Studio 2008, for people who want to create custom tokens. It will look like this once it is installed, from the Add New Item menu:

I will be doing the same for File Splitting Strategies very soon.
Justin (who didn't leave a last name) left a comment on how to debug MMC 3.0 snapins in Windows 7 x64 and Visual Studio 2008. I want to put this on its own blog post, so that I can find it easier. I'll just repost Justin's comment here:
I recently struck this problem with VS2008 on Windows 7 x64 as well.
I eventually found a solution :)
The solution is to directly use the 32 bit version of mmc at this path:
C:\Windows\SysWOW64\mmc.exe rather than the one in System32.
you still need the -32 flag as in your screenshot.
When you try and debug via "C:\Windows\System32\mmc.exe -32" what actually happens is the debugger attaches to the 64bit version which starts the 32bit version(in SysWOW64) and then closes itself hence why it stops debugging immediately.
You can start the snapin that you are debugging on the command line. This is extremely convinient. Here's a screenshot with Justin's findings:

This is on the project's properties page, on the "Debug" tab.
Now, if I could just figure out how to get the keyboard shortcuts back. They disappeared a couple days ago, and haven't been able to get them back. *boggle*

I got to play with Visual Studio 2010 today, while I was recuperating from a migraine. I didn't see anything revolutionary right away, but I haven't dug in deep yet. The one word I would use to describe it is "pretty." Here are some screenshots.
This is the Start window. This is what you see when you first fire up Visual Studio 2010 Professional:

Here is the screen for the Projects link above:

Here is the screen for the Visual Studio link above:

And here is what everybody wanted to see, the IDE open with a project. This solution has 22 projects:

I am running Visual Studio 2010 in a VMWare image running Windows 7 Ultimate. This image had 512 megs of RAM. It was a bit slow, but that's to be expected with that little RAM. I'll make another test with 1 Gig RAM, and see how that goes.
After much work reinstalling Vista and Visual Studio 2008, I found out that I still can't debug 32bit MMC 3.0 snapins in Vista 64. You still need to attach the debugger manually to the running process. Unfortunately, this means that you won't be able to debug stuff while your code is loading.
I really was not ready to go back to 32 bit, so I compromised by creating a VMWare image that contains Windows XP SP3, Visual Studio 2008 SP1, and all the other necessary dev tools.
I now have a rig that I know always lets me debug. TortoiseSVN makes it simple to keep my VM and desktop synched.
Score that a WIN!
Well, I found out that Visual Studio 2005 breakpoints do not work in Windows Vista 64bit. It is a known issue.
Just-In-Time (JIT) Debugging of an elevated process will fail
The workaround is to attach the debugger manually. Bummer! I think I'm going to migrate PainlessSVN to Visual Studio 2008. Thankfully, I already have it installed.
I had a issue where I didn't know how in the heck to debug PainlessSVN in my new Windows Ultimate x64. Thankfully, I found the answer after only a couple Google queries.
MMC 3.0 comes in both x32 and x64 versions. Normally, I would call the mmc.exe host with just C:\Windows\System32\mmc.exe in the debug tab of the project properties. I found out that I needed to append a -32 parameter at the end of this path. Here is how it is setup in the tab:

That command-line argument that I highlighted in red is very important.
I found the answer in this blog post: http://blogs.technet.com/askperf/archive/2008/04/25/controlling-your-mmc-snap-ins-on-64-bit-operating-systems.aspx
I finally took the plunge and change the default colors for my Visual Studio text editor. I tried a few from http://idehotornot.ning.com I liked Pill Crusher 2008 the best. The nice thing about it is that it can be used in both VS2005 and VS2008. All that is needed is to open the settings in your favorite text editor, then change this node:
ApplicationIdentity version="9.0"
to this:
ApplicationIdentity version="8.0"
VS2005 is 8.0, while 9.0 is VS2008