In the current JetPack version, I think Publicize calculates a tweet's length the wrong way.
By default, the tweet's text contains the post's title and a link to such. However, if the title is too long, it's cut off.
Now that's a nice thing, but I think the plugin counts all chars of the link to the post as text of the tweet. But Links in Tweets are always 22/23 Chars long, depending on whether http or https is used.
As an example, this is a faulty tweet of mine: https://twitter.com/TacticalCode/status/328494462391173122
Note that the post's title actually is
Leistungsschutzrecht 2.1 – FreeLens verklagt Google wegen Bildersuche
and therefore 69 chars long.
Title(69 chars) + space + url(22 chars) = 92 Chars, fits all in one tweet
Title(69 chars) + space + ...(1 char) + Full URL length(108 chars) = 178 chars.
So the title is cut off after a maximum of 140-(108+1+1) = 30 chars, which isn't correct.
Could any dev please fix this in an upcoming version of JetPack?
(Note that I use the full permalink to my posts, see http://wordpress.org/support/topic/publicize-bug?replies=3 )