I have noticed no change, but that's likely due to your ability to edit your posts multiple times before I ever actually see them. ;) So I'm going to guess and say it's worsened your typing ability, based on the fact that every time my hands and fingers have to learn (or re-learn) to do something new (juggling, playing zils, knitting), it screws with my typing ability for awhile, until I get very comfortable at doing the new thing and do it and typing equally.

For me, playing guitar really limbers up my fingers. Especially doing scales.

My guess is that there isn't a significant change. If there was a change I think it would be to worsen your ability. I say that because you have to think about mandolin, and you probably didn't have to think about typing. Now you might be thinking about typing because you have to think about mandolin. But this is one of those things that you need some lab results, which I can't get from here.

I don't know about improvements to your typing, but it's definitely helped my driving skills! Thanks!

As with others, I haven't noticed a change either.

Now, I'll tell you this, somewhat related: there's a reason I don't use a Palm PDA anymore - using one completely (and so far permanently) ruined my handwriting.

Hmm. I'll go with 'worsened'.

Although to be fair, I have the distinct advantage of having noticed that your fingertips seem to be deteriorating (in an odd, mummy-like fashion) with newly formed callouses. I doubt those help much with key sensitivity.