The best that can be said is that T1 supports audio and so does play MP3 audiobooks. But it is not in any sense an audiobook reader and I would not use one for that purpose. For a dual use device cellular phones are a far more convenient choice as most have proper audiobook reader applications available for them, are far more portable, less battery hungry and generally always carried, and is what I use.
As best as I remember the T1 does remember the last position got to in an audio file so it resumes where you left off listening but that only for the last file listened to (I cannot remember if it still does this when turned off or just if in "sleep" mode). It also does not do bookmarks. So, for example, if one was listening to a book and then played some music or listened to another book, you will have lost your place in the first one.
If audiobooks are important then I don't think anyone who is used to audiobooks would think that the T1 is a convenient choice for those (I cannot comment on readers from other manufacturers, they may be the same). It is a very good eBook reader, however.