New feature suggestion : tabs interface
You might find that FoxTerm at http://foxterm.net/ meets your needs. It support multiple sessions within one instance of the program.
I tried to use it recently and their team is open to suggestions, just like the TeraTerm team.
I stuck with TeraTerm because it is more mature and feature rich.
HTH
Hi thibault,
We added the Collector application supporting the multitab interface to archive your request. Please install the Collector with Tera Term installation.
Thanks.
doda 
Tera Term
we administrate and debug networks and by definition we are connected to several network devices at the same time, it could be 10 to 15.
it is very convenient or even decisive for the use of a terminal emulator that it has tabs interface, like for example all browsers have now (firefox, chrome, IE9, IE8, opera, etc.).
I really think it is a key feature, it is easy to tell do you prefer have 11 different windows open, or only one with tabs inside ?
I have not found a previous feature request about it so I added this one.
keep up the good job !
Thibault