You can (manually) add this bit to the URL, right after the node number, before the #:
?from=0&comments_per_page=5000
This is just a workaround, not a solution to the bug.

Or you can add manually the appropriate page number, as in http://www.typophile.com/node/81129?page=1#comment-461794 ; notice that it is "page=1" and it is page 2 (it is always one less). The timestamp should indeed contain the page number (I added a blank before the semicolon for the link to work).

Yes, I successfully added the page number manually as Michel suggests when I tried it, but seeing Florian's workaround I wonder if Michel's would break based on having a different setting for comments per page. Is that a user-adjustable setting, by the way?

Is that a user-adjustable setting?
No, at the moment not. But it has been adjusted globally in the past

Also, there is the (unlikely) possibility that you want to link to comment no. n+1 (n = maximum number of comments per page), and later on, an older comment gets deleted, making the one in question the n-th.

I just counted (in fact, I wrote a script to count) the number of comments for each page of http://www.typophile.com/node/123 and I get 90 comments per page for page 1 to 7, and then less than 90 comments on page 8. What does the number 5000 then represent in comments_per_page=5000 ?

This number overrides the default maximum number of comments per page (yes, 90 – at the moment) . You can also enter a different value. But with a value as large as 5000, you practically request a thread with all its comments, as a single page.

And with http://www.typophile.com/node/123?from=0&comments_per_page=5000 I indeed get a single page! Thanks.

And I think the clean solution is a link like this:

http://www.typophile.com/node/123?page=5&from=0&comments_per_page=90#com...

that specifies the page number but also the current number of comments per page, namely 90. You are then linked to the right page (and not to a single page thread) and even if the number of comments per page ever changes, the link will still be valid.