WordPress.org

How is it licensed?

GPL

Does it require PHP safe mode to be off?

laboratory tests say it doesn't; however, this needs testing in the wild (hosting environments can be very different, depending on the host's willingness to pay for a good sysadmin).

Requirements?

• Wordpress 2.0 or later
• the gd library enabled in PHP

Plugin could not be activated because it triggered a fatal error. wtf?

it's most probably due to exceeding memory_limit; Inline Gallery uses a big library (the PHP JPEG Metadata Toolkit), and eats up about 3MB of server memory when fully loaded.

Version 0.3.9 delays loading the code until it is actually needed, so this shouldn't happen any more. If it does, it probably wouldn't work anyway in your current setup (try disabling some plugins).

How many images can it display?

It depends on the available memory; benchmarks in this area are still needed.

How about speed?

Since version 0.3.9, Inline Gallery uses the Wordpress caching framework, so it can take advantage of high performance caching if needed; and since PJMT (the biggest memory hog) is loaded only when needed, a cache hit usually results in lower overall memory consumption.