Generally one has to know what TPMs and TXT and all these technologies are aimed to protect from, because there are misunderstandings.
TPMs, generally, enable 5 distinct processes, and only those:
- Integrity measurement – computation of a cryptographic hash of a platform component
- Authenticated boot – a process by which a platform's state (the sum of its components) is reliably measured and stored
- Sealed storage – the process of storing data on a platform in such a way that the data can only be retrieved if the platform is in a particular state
- Attestation – the process of reliably reporting the platform's current state
- Isolated execution – enables the unhindered execution of software
From the Intel perspective, TXT is the entirety of trusted computing functions including the TPM, modifications to the operation of the processor and modifications to the operation of the chipset.
Main features of TXT technology are all those of TPMs plus
- protected execution (hardware-based domain separation)
- protected memory pages (providing protection against all four different ways memory can be accessed - through software, through DMA, through GPU cards, through SMM)
- protected input
- protected graphics
- enabling trusted channels (between two computers or devices between one computer)
The Late Launch feature you mention is an optional TXT feature to enable measurements to occur after a system has been booted instead of every step of the boot processes, it's somewhat complicated.
Generally Trusted Computing is a huge project, with much research going on around the world for years, and has short term, mid term and long term goals. I must disclose here that I'm part of that research.
Now on to real implementations (although these are outside my field)
First of all, all major system manufacturers have enterprise hardware and software that makes use of TPM's, some features of it a least. Companies like Dell and HP that produce the majority of enterprise systems use software like (HP ProtectTools). In this example, pre-boot authentication is used with the help of a TPM. Microsoft has been in this research since forever, and has relased bitlocker with support for TPM before Vista. Actually bitlocker is not only about encryption: It has a separate feature named Secure Startup that implements the integrity checking part (it could be there without the encryption component). Transparent operation has to do with authentication - it can work in pre-boot auth mode as well. Also security software ventors, like symantec and mcaffee have software that relies or makes use of TPMs.
Now, I'm not aware of any other commercial or ready-for-use open source software dealing with TPM's and attestation or any other feature. (but as I said I haven't looked much, maybe another member knows more).
If you want experimental tools, proof of concept software or just papers and specifications, there are lots of that - as I said there are long-term goals in the project, and attestation is one of the long-term goals. Here is an example, reference implementation of the software stack necessary to support all features of a TPM in linux: http://www.opentc.net/publications/OpenTC_PET_prototype_documentation_v1.0.pdf (software is at http://www.opentc.net )
Just to intrigue the readers, Network Access Control is an active area of research - commercial tools may exist on that one already. The general idea in NAC using TPM's is of course to only allow a device in a network if it can be verified as secure by providing specific measurements, not only on the integrity of the booted software, but also on the level of patches applied, the anti-virus definitions, the firewall configuration... Other examples of research: Secure software download, as in a mobile carier that needs to update a phone's firmware over the air securely, specifically the software of the Software Defined Radio. Of course, Digital Video Broadcasting (DVB) is an area or research - dvb receivers already use smartcards to store keys, TPM's can be used instead.
Very-long term goals? Imagine a world where every system and mobile device has a TPM: a cryptographic coprocessor, secure storage.. and can generate public key pairs on demand, without user interaction: a worldwide PKI - research is ongoing on how to manage and what to do with that!
I think i've drifted far than the scope of the question so this should be enough.