Lukas is making another attempt at jumpstarting PDO development. I welcome this effort, and will do what I can to help fill in details and make suggestions. Unfortunately, I'm just way too busy with work to be able to commit to more than that.
I also wanted to share some of my thoughts on why PDO has been in a holding pattern for a while, so that more people are aware of it and can work to avoid repeating the same mistakes.
The first thing to note is that the guts of PDO were hard to develop. The PHP script facing API sounds simple enough, but the underlying libraries for each different databases work in different ways, and it was and is a challenge to build PDO in such a way that it can work in the most efficient way.
The second thing, which is really a follow-on from the first, is that the database libraries are complex and nuanced. Some are relatively simple (especially SQLite and MySQL) and others are complex in divergent ways (ODBC and Oracle). Making a great PDO necessitates having experts in each of those APIs and databases around as contributors, both for the core implementation and for unit tests.
Thirdly, there are a lot of databases out there. That requires a lot of resources for the PDO developers to do a good job; not just different database products, but also different versions of those products, need to be tested against. This is also very time consuming.
This boils down to a lot of effort.
Personally, I enjoy working hard. Tricky problems are the most satisfying kind to solve! However, working hard when there is no payoff is the least enjoyable kind of work.
For a successful PDO, there needs to be "payoff" for the contributors to keep them happy and working at it. In a commercial context, where someone sponsors development, the payoff is typically in the form of a paycheck to help cover the bills. In a FOSS context, the payoff may be satisfaction from working on hobby coding, may be vanity in wanting recognition and appreciation from peers or end-users or may be seen as effort to help build out a resume for future career opportunities. There may be other motivating factors too.
I've talked in the past about FOSS being "Itch Driven Development". So long as the contributors feel the need to scratch their respective itches, they'll keep on doing it. They'll stop if the itch goes away, or if the scratching leads to bleeding.
Bleeding is stuff that detracts from or otherwise lessens the payoff. In a commercial context this could manifest as something that wastes time (and time is money). In a FOSS context, this may also be the result of vocal and/or abusive or otherwise negative sentiments from peers or others in the community.
Bleeding is bad for the whole group because it can take a long time for those that were bleeding to want to try their hands at scratching again. Whatever form the renewed PDO development takes, it would do well to try to avoid bleeding. One way to do this is to follow the advice of Bill and Ted and "Be Excellent To Each Other".
At the end of the day, PDO (and PHP) is largely a volunteer effort, which means that it is something that will be worked on in the spare time of the contributors. Because it is hard work, the payoff needs to be enough for them to individually opt to work on it after a hard day at work instead of choosing alternatives, like family, beer or Xbox.
If you're willing and able to help improve PDO by contributing development effort and/or unit tests, please make yourselves known on the PDO mailing list. We need a critical mass to reduce the effort that any one person needs to make, and once we have momentum on our side, I think that PDO can be improved rather rapidly.