I'm rather pleased, as this is intended to be the client component of my MMS-LJ gateway, it's also the first .NET code I've written. Currently I'm using the flat interface to LiveJournal to send hardwired messages, with the date dynamically generated to prove that I can assemble HTTP POST query strings on the fly.
The next step is to write an HTML encoder for text blocks, and use that to embed a generic text block as the event element of the postevent. That's going to be a little more complex, and will entail me learning C# regexps. But as they're ripped off from Perl, it shouldn't be too much of a learning curve.